[SPARK-11837][EC2] python3 compatibility for launching ec2 m3 instances
[SPARK-11837][EC2] python3 compatibility for launching ec2 m3 instances

this currently breaks for python3 because `string` module doesn't have `letters` anymore, instead `ascii_letters` should be used

Author: Mortada Mehyar <mortada.mehyar@gmail.com>

Closes #9797 from mortada/python3_fix.

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