scripts: build-docker tag and use ENTRYPOINT
scripts: build-docker tag and use ENTRYPOINT

Use ENTRYPOINT so people can specify flags to etcd without providing the
binary.

Thanks to @hugod in IRC for pointing this out.

dannysauer/etcd,njharman/etcd,beni55/etcd,nkhare/etcd,bspline/etcd,cchamplin/etcd,gae123/etcd,olark/etcd,gtank/etcd,tempbottle/etcd,Winslett/etcd,glevand/coreos--etcd,lumjjb/etcd,luxas/etcd,justintung/etcd,combk8s/etcd,justintung/etcd,svdata/etcd,heyitsanthony/etcd,bluebreezecf/etcd,glensc/etcd,kingland/etcd,cognusion/etcd,improbable-io/etcd,shafreeck/etcd,heyitsanthony/etcd,delkyd/etcd,purpleidea/etcd,cockroachdb/etcd,fgbreel/etcd,pauldallen/etcd,chai2010/etcd,ylong/etcd,jmptrader/etcd,nekto0n/etcd,tguangch/etcd,steveeJ/etcd,dannysauer/etcd,purpleidea/etcd,xdlinear/etcd,giantswarm/etcd,fgbreel/etcd,mike-lerch/etcd,QuantiumTechnology/etcd,ylong/etcd,hpcloud/etcd,hongbinz/etcd,giantswarm/etcd,tamird/etcd,HideoYamauchi/etcd,gyuho/etcd,qqsun8819/etcd,sinsharat/etcd,devfreesg/etcd,etcd-io/etcd,mwitkow/etcd,csuideal/etcd,mqliang/etcd,bspline/etcd,bdarnell/etcd,beni55/etcd,mickep76/etcd,junxu/etcd,axingblog/etcd,njucslqq/etcd,ktateish/etcd,yifan-gu/etcd,honeyqa/etcd,zaphod-concur/etcd,polvi/etcd,whuwxl/etcd,plasticbox/etcd,gityf/etcd,qiaochao911/etcd,joshix/etcd,mqliang/etcd,insionng/etcd,njucslqq/etcd,CrazyJvm/etcd,jchauncey/etcd,cchamplin/etcd,kkaneda/etcd,Eagle-X/etcd,visheshnp/etcd,ktateish/etcd,insionng/etcd,delkyd/etcd,es-chow/etcd,hroyrh/etcd,youxidev/etcd,shawnps/etcd,whuwxl/etcd,xiang90/etcd,gae123/etcd,oscarrr110/etcd,gtank/etcd,armstrongli/etcd,nekto0n/etcd,freeloop1114/etcd,svdata/etcd,jeremyeder/etcd,endocode/etcd,jeremyeder/etcd,lorneli/etcd,oscarrr110/etcd,glycerine/etcd,fasaxc/etcd,xueshanf/etcd,spacejam/etcd,barakmich/etcd,ajityagaty/etcd,qqsun8819/etcd,snailwalker/etcd,xychu/etcd,steveeJ/etcd,iamqizhao/etcd,jmptrader/etcd,gosharplite/etcd,asim/etcd,li-ang/etcd,CrazyJvm/etcd,jonboulle/etcd,glevand/coreos--etcd,fanminshi/etcd,YuleiXiao/etcd,rnaveiras/etcd,handsomesun/etcd,betawaffle/etcd,junxu/etcd,lzbgt/etcd,fanminshi/etcd,akauppi/etcd,coreos/etcd,betawaffle/etcd,raoofm/etcd,achanda/etcd,crandles/etcd,sayden/etcd,crandles/etcd,wantonsolutions/dinv-etcd,shakefu/etcd,insequent/etcd,sofuture/etcd,sebrandon1/etcd,lzbgt/etcd,xiang90/etcd,etcd-io/etcd,wfxiang08/etcd,glensc/etcd,msanterre/etcd,achanda/etcd,dnaeon/etcd,chipironcin/etcd,fasaxc/etcd,Timer/etcd,yudai/etcd,combk8s/etcd,jefby/etcd,openedbox/etcd,cognusion/etcd,siddontang/etcd,bakins/etcd,li-ang/etcd,asim/etcd,ajityagaty/etcd,wowsoso/etcd,xueshanf/etcd,SivagnanamCiena/etcd,cockroachdb/etcd,QuantiumTechnology/etcd,nkhare/etcd,chenbaihu/etcd,jlamillan/etcd,YuleiXiao/etcd,dalanlan/etcd,OyTao/etcd_learning,snailwalker/etcd,onlyjob/etcd,jravetch/etcd,onlyjob/etcd,rnaveiras/etcd,ecnahc515/etcd,akauppi/etcd,jchauncey/etcd,yichengq/etcd,shakefu/etcd,wantonsolutions/dinv-etcd,ecnahc515/etcd,zaphod-concur/etcd,mischief/etcd,chai2010-playground/etcd,csuideal/etcd,kingland/etcd,buaazp/etcd,kkaneda/etcd,mitake/etcd,princeqjzh/etcd,dalanlan/etcd,tangkun75/etcd,imzhulei/etcd,OyTao/etcd_learning,mischief/etcd,linuxcer/etcd,sebschrader/etcd,msanterre/etcd,a-robinson/etcd,tangkun75/etcd,vimalk78/etcd,gouyang/etcd,hroyrh/etcd,mike-lerch/etcd,sayden/etcd,chai2010-playground/etcd,tguangch/etcd,jefby/etcd,xdlinear/etcd,westhood/etcd,luxas/etcd,HideoYamauchi/etcd,mkumatag/etcd,honeyqa/etcd,mkumatag/etcd,mwitkow-io/etcd,robszumski/etcd,etcd-io/etcd,wowsoso/etcd,chipironcin/etcd,hongchaodeng/etcd,mgoelzer/etcd-fork2,arthurcolle/etcd,arthurcolle/etcd,Eagle-X/etcd,raoofm/etcd,shafreeck/etcd,pauldallen/etcd,spacejam/etcd,elimisteve/etcd,openedbox/etcd,mickep76/etcd,bdarnell/etcd,rchicoli/etcd,fasaxc/etcd,devfreesg/etcd,rchicoli/etcd,improbable-io/etcd,chai2010/etcd,bakins/etcd,insequent/etcd,hzy001/etcd,nieanan/etcd,handsomesun/etcd,swingbach/etcd,a-robinson/etcd,princeqjzh/etcd,shawnps/etcd,gyuho/etcd,Timer/etcd,gosharplite/etcd,ravigadde/etcd,StorReduce/etcd,linuxcer/etcd,iamqizhao/etcd,chenbaihu/etcd,tempbottle/etcd,bluebreezecf/etcd,mwitkow/etcd,axingblog/etcd,Yhgenomics/etcd,buaazp/etcd,youxidev/etcd,yudai/etcd,offscale/etcd,elimisteve/etcd,ravigadde/etcd,jlamillan/etcd,jravetch/etcd,westhood/etcd,TheHippo/etcd,jonboulle/etcd,olark/etcd,glycerine/etcd,pengzj/etcd,ajityagaty/etcd,robszumski/etcd,qiaochao911/etcd,yifan-gu/etcd,visheshnp/etcd,sebschrader/etcd,StorReduce/etcd,yyljlyy/etcd,njharman/etcd,sebrandon1/etcd,dnaeon/etcd,sofuture/etcd,plasticbox/etcd,TheHippo/etcd,imzhulei/etcd,hongbinz/etcd,armstrongli/etcd,xebitstudios/etcd,xychu/etcd,tamird/etcd,mgoelzer/etcd-fork2,barakmich/etcd,mkumatag/etcd,mwitkow-io/etcd,mitake/etcd,joshix/etcd,lorneli/etcd,swingbach/etcd,xebitstudios/etcd,dterei/etcd,rnaveiras/etcd,coreos/etcd,dterei/etcd,mqliang/etcd,Winslett/etcd,yyljlyy/etcd,siddontang/etcd,hongchaodeng/etcd,Yhgenomics/etcd,nieanan/etcd,hpcloud/etcd,hzy001/etcd,vimalk78/etcd,gouyang/etcd,es-chow/etcd,SivagnanamCiena/etcd,pengzj/etcd,freeloop1114/etcd,yichengq/etcd,lumjjb/etcd,wfxiang08/etcd,endocode/etcd,offscale/etcd,sinsharat/etcd,wantonsolutions/dinv-etcd,gityf/etcd,polvi/etcd