HOTFIX: Minor improvements to make-distribution.sh
HOTFIX: Minor improvements to make-distribution.sh

1. Renames $FWDIR to $SPARK_HOME (vast majority of diff).
2. Use Spark-provided Maven.
3. Logs build flags in the RELEASE file.

Author: Patrick Wendell <pwendell@gmail.com>

Closes #3973 from pwendell/master and squashes the following commits:

340a2fa [Patrick Wendell] HOTFIX: Minor improvements to make-distribution.sh

sahilTakiar/spark,1haodian/spark,lvdongr/spark,liyichao/spark,ddna1021/spark,WeichenXu123/spark,szhem/spark,adrian-ionescu/apache-spark,guoxiaolongzte/spark,spark-test/spark,icexelloss/spark,apache/spark,gioenn/xSpark,ddna1021/spark,srowen/spark,ron8hu/spark,michalsenkyr/spark,shaneknapp/spark,lvdongr/spark,pgandhi999/spark,jlopezmalla/spark,esi-mineset/spark,shaneknapp/spark,liyichao/spark,dbtsai/spark,Panos-Bletsos/spark-cost-model-optimizer,huang1900/spark,joseph-torres/spark,jianran/spark,icexelloss/spark,bOOm-X/spark,ibm-research-ireland/sparkoscope,shaneknapp/spark,andrewor14/iolap,SnappyDataInc/spark,caneGuy/spark,holdenk/spark,SHASHANKB/spark,matthewfranglen/spark,liutang123/spark,mahak/spark,jkbradley/spark,saturday-shi/spark,facaiy/spark,taroplus/spark,metamx/spark,rezasafi/spark,zzcclp/spark,alunarbeach/spark,pgandhi999/spark,aray/spark,facaiy/spark,JerryLead/spark,apache-spark-on-k8s/spark,dhruve/spark,WeichenXu123/spark,lxsmnv/spark,zzcclp/spark,cloud-fan/spark,aosagie/spark,saltstar/spark,aokolnychyi/spark,wzhfy/spark,pronix/spark,wzhfy/spark,chuckchen/spark,ibm-research-ireland/sparkoscope,map222/spark,tengpeng/spark,chuckchen/spark,mahak/spark,ahnqirage/spark,gengliangwang/spark,gengliangwang/spark,ptkool/spark,taroplus/spark,tejasapatil/spark,zuotingbing/spark,hhbyyh/spark,wangyum/spark,jrshust/spark,bdrillard/spark,rezasafi/spark,saturday-shi/spark,dbtsai/spark,nlalevee/spark,wangmiao1981/spark,UndeadBaneGitHub/spark,michalsenkyr/spark,darionyaphet/spark,andrewor14/spark,minixalpha/spark,bOOm-X/spark,goldmedal/spark,wzhfy/spark,actuaryzhang/spark,janewangfb/spark,vinodkc/spark,cloud-fan/spark,jiangxb1987/spark,techaddict/spark,MLnick/spark,jkbradley/spark,liyichao/spark,SnappyDataInc/spark,esi-mineset/spark,bravo-zhang/spark,panfengfeng/spark,liutang123/spark,skonto/spark,szhem/spark,JerryLead/spark,ueshin/apache-spark,WindCanDie/spark,loneknightpy/spark,kissmetrics/spark,1haodian/spark,sureshthalamati/spark,spark-test/spark,poffuomo/spark,kimoonkim/spark,ajaysaini725/spark,ahnqirage/spark,WindCanDie/spark,saltstar/spark,wzhfy/spark,milliman/spark,hhbyyh/spark,shubhamchopra/spark,hhbyyh/spark,WindCanDie/spark,tengpeng/spark,facaiy/spark,wangmiao1981/spark,janewangfb/spark,guoxiaolongzte/spark,stanzhai/spark,zhouyejoe/spark,Aegeaner/spark,bdrillard/spark,jianran/spark,zuotingbing/spark,alunarbeach/spark,hvanhovell/spark,sureshthalamati/spark,saltstar/spark,ueshin/apache-spark,dbtsai/spark,esi-mineset/spark,rekhajoshm/spark,joseph-torres/spark,LantaoJin/spark,apache/spark,ericvandenbergfb/spark,nilsgrabbert/spark,michalsenkyr/spark,rikima/spark,panfengfeng/spark,yanboliang/spark,guoxiaolongzte/spark,apache/spark,esi-mineset/spark,SHASHANKB/spark,techaddict/spark,shuangshuangwang/spark,andrewor14/iolap,kiszk/spark,facaiy/spark,wzhfy/spark,lxsmnv/spark,ron8hu/spark,cin/spark,maropu/spark,hvanhovell/spark,goldmedal/spark,gioenn/xSpark,metamx/spark,alunarbeach/spark,zhouyejoe/spark,ioana-delaney/spark,liutang123/spark,1haodian/spark,BryanCutler/spark,LantaoJin/spark,hvanhovell/spark,janewangfb/spark,WeichenXu123/spark,apache/spark,lxsmnv/spark,darionyaphet/spark,rikima/spark,dhruve/spark,aosagie/spark,saturday-shi/spark,darionyaphet/spark,mahak/spark,spark-test/spark,huang1900/spark,WeichenXu123/spark,highfei2011/spark,brad-kaiser/spark,kimoonkim/spark,zzcclp/spark,patrick-nicholson/spark,jkbradley/spark,icexelloss/spark,lvdongr/spark,byakuinss/spark,brad-kaiser/spark,andrewor14/spark,sureshthalamati/spark,ron8hu/spark,dongjoon-hyun/spark,markhamstra/spark,skonto/spark,hhbyyh/spark,aokolnychyi/spark,bravo-zhang/spark,lvdongr/spark,mahak/spark,cin/spark,publicRoman/spark,1haodian/spark,yanboliang/spark,kissmetrics/spark,Panos-Bletsos/spark-cost-model-optimizer,yanboliang/spark,minixalpha/spark,kiszk/spark,WindCanDie/spark,xflin/spark,cin/spark,ron8hu/spark,publicRoman/spark,tengpeng/spark,goldmedal/spark,saturday-shi/spark,jlopezmalla/spark,nchammas/spark,jiangxb1987/spark,UndeadBaneGitHub/spark,setjet/spark,markhamstra/spark,liutang123/spark,zero323/spark,1haodian/spark,someorz/spark,bravo-zhang/spark,guoxiaolongzte/spark,srowen/spark,mzl9039/spark,SnappyDataInc/spark,markhamstra/spark,eyalfa/spark,rezasafi/spark,hvanhovell/spark,mzl9039/spark,gengliangwang/spark,byakuinss/spark,wzhfy/spark,chuckchen/spark,xflin/spark,MLnick/spark,ConeyLiu/spark,jianran/spark,jkbradley/spark,andrewor14/iolap,dbtsai/spark,debugger87/spark,metamx/spark,chuckchen/spark,Aegeaner/spark,michalsenkyr/spark,techaddict/spark,sachintyagi22/spark,metamx/spark,janewangfb/spark,loneknightpy/spark,saturday-shi/spark,kevinyu98/spark,kiszk/spark,debugger87/spark,ueshin/apache-spark,xflin/spark,esi-mineset/spark,yanboliang/spark,nilsgrabbert/spark,gioenn/xSpark,patrick-nicholson/spark,apache/spark,shubhamchopra/spark,minixalpha/spark,akopich/spark,gengliangwang/spark,ajaysaini725/spark,apache-spark-on-k8s/spark,caneGuy/spark,mzl9039/spark,zhouyejoe/spark,akopich/spark,UndeadBaneGitHub/spark,bravo-zhang/spark,wangyum/spark,ericvandenbergfb/spark,shuangshuangwang/spark,milliman/spark,xuanyuanking/spark,MLnick/spark,rekhajoshm/spark,kimoonkim/spark,narahari92/spark,jianran/spark,ddna1021/spark,caneGuy/spark,patrick-nicholson/spark,apache-spark-on-k8s/spark,wangmiao1981/spark,dongjoon-hyun/spark,actuaryzhang/spark,aray/spark,minixalpha/spark,eyalfa/spark,pgandhi999/spark,highfei2011/spark,huang1900/spark,gioenn/xSpark,mike0sv/spark,cin/spark,pronix/spark,aokolnychyi/spark,UndeadBaneGitHub/spark,shuangshuangwang/spark,milliman/spark,ptkool/spark,witgo/spark,zhouyejoe/spark,spark-test/spark,hvanhovell/spark,maropu/spark,rikima/spark,wangyum/spark,haowu80s/spark,byakuinss/spark,xuanyuanking/spark,poffuomo/spark,panfengfeng/spark,ericvandenbergfb/spark,adrian-ionescu/apache-spark,bravo-zhang/spark,ibm-research-ireland/sparkoscope,rezasafi/spark,shubhamchopra/spark,gioenn/xSpark,ptkool/spark,icexelloss/spark,aokolnychyi/spark,huang1900/spark,pronix/spark,nlalevee/spark,aokolnychyi/spark,poffuomo/spark,MLnick/spark,caneGuy/spark,BryanCutler/spark,patrick-nicholson/spark,tejasapatil/spark,big-pegasus/spark,poffuomo/spark,HyukjinKwon/spark,milliman/spark,haowu80s/spark,rikima/spark,jkbradley/spark,kevinyu98/spark,Aegeaner/spark,wangyum/spark,dbtsai/spark,rednaxelafx/apache-spark,jiangxb1987/spark,BryanCutler/spark,icexelloss/spark,ioana-delaney/spark,setjet/spark,narahari92/spark,maropu/spark,nchammas/spark,cloud-fan/spark,patrick-nicholson/spark,shubhamchopra/spark,publicRoman/spark,janewangfb/spark,ueshin/apache-spark,Aegeaner/spark,joseph-torres/spark,aosagie/spark,bOOm-X/spark,joseph-torres/spark,wangmiao1981/spark,ioana-delaney/spark,bOOm-X/spark,zero323/spark,szhem/spark,zzcclp/spark,byakuinss/spark,JerryLead/spark,zuotingbing/spark,vinodkc/spark,esi-mineset/spark,nchammas/spark,taroplus/spark,darionyaphet/spark,zhouyejoe/spark,andrewor14/iolap,dongjoon-hyun/spark,markhamstra/spark,xuanyuanking/spark,goldmedal/spark,aokolnychyi/spark,srowen/spark,narahari92/spark,bdrillard/spark,zhouyejoe/spark,dongjoon-hyun/spark,stanzhai/spark,big-pegasus/spark,hhbyyh/spark,mahak/spark,sureshthalamati/spark,apache-spark-on-k8s/spark,panfengfeng/spark,HyukjinKwon/spark,mdespriee/spark,ericvandenbergfb/spark,mdespriee/spark,sahilTakiar/spark,JoshRosen/spark,WeichenXu123/spark,rednaxelafx/apache-spark,ajaysaini725/spark,cin/spark,dongjoon-hyun/spark,metamx/spark,JerryLead/spark,milliman/spark,nlalevee/spark,bOOm-X/spark,xuanyuanking/spark,mdespriee/spark,ahnqirage/spark,byakuinss/spark,cloud-fan/spark,SHASHANKB/spark,HyukjinKwon/spark,LantaoJin/spark,akopich/spark,dongjoon-hyun/spark,dhruve/spark,kiszk/spark,eyalfa/spark,tejasapatil/spark,srowen/spark,jkbradley/spark,apache/spark,HyukjinKwon/spark,maropu/spark,andrewor14/iolap,MLnick/spark,kimoonkim/spark,setjet/spark,stanzhai/spark,zuotingbing/spark,jlopezmalla/spark,shuangshuangwang/spark,goldmedal/spark,aosagie/spark,bravo-zhang/spark,techaddict/spark,highfei2011/spark,panfengfeng/spark,kevinyu98/spark,taroplus/spark,rekhajoshm/spark,pgandhi999/spark,loneknightpy/spark,skonto/spark,sahilTakiar/spark,michalsenkyr/spark,huang1900/spark,Panos-Bletsos/spark-cost-model-optimizer,sureshthalamati/spark,aosagie/spark,ConeyLiu/spark,actuaryzhang/spark,pronix/spark,taroplus/spark,jrshust/spark,alunarbeach/spark,BryanCutler/spark,witgo/spark,mike0sv/spark,darionyaphet/spark,wzhfy/spark,ibm-research-ireland/sparkoscope,szhem/spark,setjet/spark,jianran/spark,kiszk/spark,haowu80s/spark,publicRoman/spark,xflin/spark,debugger87/spark,wangmiao1981/spark,tejasapatil/spark,tejasapatil/spark,setjet/spark,ahnqirage/spark,apache-spark-on-k8s/spark,xuanyuanking/spark,loneknightpy/spark,aray/spark,nilsgrabbert/spark,szhem/spark,jianran/spark,BryanCutler/spark,map222/spark,yanboliang/spark,SHASHANKB/spark,dbtsai/spark,sahilTakiar/spark,saltstar/spark,yanboliang/spark,ConeyLiu/spark,holdenk/spark,saturday-shi/spark,cloud-fan/spark,aray/spark,chuckchen/spark,pronix/spark,eyalfa/spark,ptkool/spark,publicRoman/spark,adrian-ionescu/apache-spark,chuckchen/spark,publicRoman/spark,witgo/spark,yanboliang/spark,Aegeaner/spark,JoshRosen/spark,jlopezmalla/spark,someorz/spark,joseph-torres/spark,maropu/spark,markhamstra/spark,WeichenXu123/spark,WindCanDie/spark,srowen/spark,patrick-nicholson/spark,adrian-ionescu/apache-spark,kevinyu98/spark,liutang123/spark,witgo/spark,mdespriee/spark,ahnqirage/spark,sahilTakiar/spark,tejasapatil/spark,ericvandenbergfb/spark,jrshust/spark,JerryLead/spark,akopich/spark,HyukjinKwon/spark,ioana-delaney/spark,ConeyLiu/spark,ioana-delaney/spark,goldmedal/spark,shaneknapp/spark,rekhajoshm/spark,taroplus/spark,ddna1021/spark,bOOm-X/spark,SnappyDataInc/spark,ioana-delaney/spark,JoshRosen/spark,lxsmnv/spark,mike0sv/spark,liyichao/spark,mike0sv/spark,jlopezmalla/spark,janewangfb/spark,Panos-Bletsos/spark-cost-model-optimizer,tengpeng/spark,wangyum/spark,actuaryzhang/spark,MLnick/spark,poffuomo/spark,tengpeng/spark,wangyum/spark,mdespriee/spark,lvdongr/spark,vinodkc/spark,rezasafi/spark,shuangshuangwang/spark,ibm-research-ireland/sparkoscope,joseph-torres/spark,shubhamchopra/spark,maropu/spark,sachintyagi22/spark,lxsmnv/spark,SHASHANKB/spark,kiszk/spark,kimoonkim/spark,techaddict/spark,dhruve/spark,michalsenkyr/spark,kiszk/spark,poffuomo/spark,xuanyuanking/spark,aray/spark,bOOm-X/spark,jlopezmalla/spark,dhruve/spark,someorz/spark,michalsenkyr/spark,mzl9039/spark,JoshRosen/spark,zzcclp/spark,janewangfb/spark,andrewor14/iolap,icexelloss/spark,jiangxb1987/spark,haowu80s/spark,wangmiao1981/spark,debugger87/spark,ron8hu/spark,caneGuy/spark,esi-mineset/spark,ptkool/spark,andrewor14/spark,stanzhai/spark,byakuinss/spark,BryanCutler/spark,ahnqirage/spark,rekhajoshm/spark,minixalpha/spark,ConeyLiu/spark,andrewor14/spark,hhbyyh/spark,ioana-delaney/spark,mzl9039/spark,lvdongr/spark,hvanhovell/spark,rikima/spark,lvdongr/spark,UndeadBaneGitHub/spark,pgandhi999/spark,kissmetrics/spark,eyalfa/spark,nlalevee/spark,facaiy/spark,caneGuy/spark,shuangshuangwang/spark,SHASHANKB/spark,publicRoman/spark,shubhamchopra/spark,loneknightpy/spark,aray/spark,hhbyyh/spark,kevinyu98/spark,brad-kaiser/spark,holdenk/spark,andrewor14/spark,SHASHANKB/spark,caneGuy/spark,debugger87/spark,ConeyLiu/spark,vinodkc/spark,huang1900/spark,nchammas/spark,spark-test/spark,markhamstra/spark,Aegeaner/spark,UndeadBaneGitHub/spark,andrewor14/spark,srowen/spark,lxsmnv/spark,ibm-research-ireland/sparkoscope,MLnick/spark,taroplus/spark,highfei2011/spark,1haodian/spark,rekhajoshm/spark,ajaysaini725/spark,cloud-fan/spark,andrewor14/iolap,WindCanDie/spark,saturday-shi/spark,zzcclp/spark,someorz/spark,aray/spark,adrian-ionescu/apache-spark,joseph-torres/spark,dhruve/spark,mike0sv/spark,stanzhai/spark,icexelloss/spark,nlalevee/spark,spark-test/spark,loneknightpy/spark,kevinyu98/spark,rednaxelafx/apache-spark,wangyum/spark,cin/spark,LantaoJin/spark,shubhamchopra/spark,szhem/spark,aosagie/spark,guoxiaolongzte/spark,dongjoon-hyun/spark,rikima/spark,akopich/spark,witgo/spark,kimoonkim/spark,jiangxb1987/spark,liyichao/spark,eyalfa/spark,someorz/spark,szhem/spark,techaddict/spark,debugger87/spark,LantaoJin/spark,tejasapatil/spark,panfengfeng/spark,shuangshuangwang/spark,nilsgrabbert/spark,highfei2011/spark,kissmetrics/spark,milliman/spark,big-pegasus/spark,liutang123/spark,mdespriee/spark,ptkool/spark,xuanyuanking/spark,nilsgrabbert/spark,actuaryzhang/spark,darionyaphet/spark,zuotingbing/spark,saltstar/spark,nilsgrabbert/spark,zero323/spark,mahak/spark,bdrillard/spark,srowen/spark,actuaryzhang/spark,Aegeaner/spark,cin/spark,jrshust/spark,mike0sv/spark,stanzhai/spark,narahari92/spark,big-pegasus/spark,holdenk/spark,LantaoJin/spark,zero323/spark,ron8hu/spark,kissmetrics/spark,gioenn/xSpark,alunarbeach/spark,byakuinss/spark,skonto/spark,sahilTakiar/spark,LantaoJin/spark,akopich/spark,aosagie/spark,nlalevee/spark,sachintyagi22/spark,akopich/spark,aokolnychyi/spark,bdrillard/spark,poffuomo/spark,narahari92/spark,jkbradley/spark,jrshust/spark,huang1900/spark,nchammas/spark,gengliangwang/spark,nchammas/spark,someorz/spark,metamx/spark,ddna1021/spark,milliman/spark,hvanhovell/spark,ron8hu/spark,JerryLead/spark,setjet/spark,gioenn/xSpark,markhamstra/spark,minixalpha/spark,big-pegasus/spark,eyalfa/spark,rednaxelafx/apache-spark,narahari92/spark,apache/spark,sureshthalamati/spark,rikima/spark,WeichenXu123/spark,kissmetrics/spark,wangmiao1981/spark,apache-spark-on-k8s/spark,guoxiaolongzte/spark,debugger87/spark,xflin/spark,setjet/spark,nlalevee/spark,haowu80s/spark,minixalpha/spark,JoshRosen/spark,zero323/spark,big-pegasus/spark,liyichao/spark,Panos-Bletsos/spark-cost-model-optimizer,andrewor14/spark,alunarbeach/spark,ueshin/apache-spark,vinodkc/spark,JoshRosen/spark,ericvandenbergfb/spark,kimoonkim/spark,UndeadBaneGitHub/spark,ericvandenbergfb/spark,darionyaphet/spark,map222/spark,brad-kaiser/spark,panfengfeng/spark,rednaxelafx/apache-spark,bravo-zhang/spark,map222/spark,map222/spark,shaneknapp/spark,tengpeng/spark,chuckchen/spark,bdrillard/spark,skonto/spark,ConeyLiu/spark,sureshthalamati/spark,alunarbeach/spark,witgo/spark,nchammas/spark,ueshin/apache-spark,skonto/spark,lxsmnv/spark,guoxiaolongzte/spark,zuotingbing/spark,spark-test/spark,jianran/spark,rednaxelafx/apache-spark,holdenk/spark,dhruve/spark,tengpeng/spark,ptkool/spark,kissmetrics/spark,saltstar/spark,maropu/spark,HyukjinKwon/spark,techaddict/spark,vinodkc/spark,shaneknapp/spark,ddna1021/spark,adrian-ionescu/apache-spark,SnappyDataInc/spark,sachintyagi22/spark,rednaxelafx/apache-spark,actuaryzhang/spark,shaneknapp/spark,brad-kaiser/spark,witgo/spark,dbtsai/spark,ahnqirage/spark,bdrillard/spark,highfei2011/spark,pgandhi999/spark,xflin/spark,adrian-ionescu/apache-spark,jiangxb1987/spark,metamx/spark,mzl9039/spark,mdespriee/spark,jlopezmalla/spark,mzl9039/spark,mike0sv/spark,WindCanDie/spark,sahilTakiar/spark,BryanCutler/spark,stanzhai/spark,sachintyagi22/spark,jrshust/spark,zzcclp/spark,pronix/spark,ibm-research-ireland/sparkoscope,zuotingbing/spark,1haodian/spark,rezasafi/spark,zero323/spark,patrick-nicholson/spark,holdenk/spark,big-pegasus/spark,brad-kaiser/spark,ajaysaini725/spark,loneknightpy/spark,skonto/spark,ddna1021/spark,highfei2011/spark,facaiy/spark,sachintyagi22/spark,goldmedal/spark,someorz/spark,liutang123/spark,nilsgrabbert/spark,JerryLead/spark,Panos-Bletsos/spark-cost-model-optimizer,gengliangwang/spark,gengliangwang/spark,Panos-Bletsos/spark-cost-model-optimizer,cloud-fan/spark,ueshin/apache-spark,ajaysaini725/spark,narahari92/spark,jrshust/spark,liyichao/spark,holdenk/spark,rekhajoshm/spark,brad-kaiser/spark,facaiy/spark,SnappyDataInc/spark,map222/spark,apache-spark-on-k8s/spark,vinodkc/spark,HyukjinKwon/spark,sachintyagi22/spark,mahak/spark,pgandhi999/spark,xflin/spark,zhouyejoe/spark,saltstar/spark,kevinyu98/spark,rezasafi/spark,jiangxb1987/spark,JoshRosen/spark,map222/spark,SnappyDataInc/spark,zero323/spark,haowu80s/spark,ajaysaini725/spark