Added parallel build option to build_travis.py
Added parallel build option to build_travis.py

Mostly to test Mihail's parallel build changes

svogl/mbed-os,cvtsi2sd/mbed-os,ryankurte/mbed-os,jpbrucker/mbed,EmuxEvans/mbed,hwfwgrp/mbed,nabilbendafi/mbed,YarivCol/mbed-os,bcostm/mbed-os,andreaslarssonublox/mbed,screamerbg/mbed,HeadsUpDisplayInc/mbed,mmorenobarm/mbed-os,ryankurte/mbed-os,GustavWi/mbed,naves-thiago/mbed-midi,cvtsi2sd/mbed-os,bikeNomad/mbed,pbrook/mbed,maximmbed/mbed,bikeNomad/mbed,devanlai/mbed,svogl/mbed-os,RonEld/mbed,pedromes/mbed,nabilbendafi/mbed,theotherjimmy/mbed,netzimme/mbed-os,bcostm/mbed-os,DanKupiniak/mbed,pbrook/mbed,HeadsUpDisplayInc/mbed,wodji/mbed,Marcomissyou/mbed,fvincenzo/mbed-os,cvtsi2sd/mbed-os,mmorenobarm/mbed-os,andcor02/mbed-os,larks/mbed,ARM-software/mbed-beetle,kjbracey-arm/mbed,cvtsi2sd/mbed-os,nabilbendafi/mbed,nabilbendafi/mbed,rosterloh/mbed,Archcady/mbed-os,bcostm/mbed-os,pi19404/mbed,rgrover/mbed,jferreir/mbed,alertby/mbed,kjbracey-arm/mbed,pedromes/mbed,betzw/mbed-os,sam-geek/mbed,svastm/mbed,bentwire/mbed,devanlai/mbed,Archcady/mbed-os,wodji/mbed,NitinBhaskar/mbed,rgrover/mbed,nabilbendafi/mbed,mikaleppanen/mbed-os,jpbrucker/mbed,bremoran/mbed-drivers,Sweet-Peas/mbed,iriark01/mbed-drivers,arostm/mbed-os,rosterloh/mbed,j-greffe/mbed-os,fahhem/mbed-os,svastm/mbed,NitinBhaskar/mbed,rgrover/mbed,monkiineko/mbed-os,Willem23/mbed,alertby/mbed,pbrook/mbed,bikeNomad/mbed,mikaleppanen/mbed-os,catiedev/mbed-os,bentwire/mbed,Tiryoh/mbed,Tiryoh/mbed,NXPmicro/mbed,svastm/mbed,fvincenzo/mbed-os,radhika-raghavendran/mbed-os5.1-onsemi,mazimkhan/mbed-os,karsev/mbed-os,pradeep-gr/mbed-os5-onsemi,ban4jp/mbed,naves-thiago/mbed-midi,nRFMesh/mbed-os,andreaslarssonublox/mbed,arostm/mbed-os,bulislaw/mbed-os,c1728p9/mbed-os,Marcomissyou/mbed,JasonHow44/mbed,nRFMesh/mbed-os,CalSol/mbed,HeadsUpDisplayInc/mbed,NXPmicro/mbed,jamesadevine/mbed,kl-cruz/mbed-os,tung7970/mbed-os,monkiineko/mbed-os,fpiot/mbed-ats,K4zuki/mbed,pedromes/mbed,JasonHow44/mbed,K4zuki/mbed,fahhem/mbed-os,bentwire/mbed,andcor02/mbed-os,jpbrucker/mbed,Willem23/mbed,pbrook/mbed,Archcady/mbed-os,JasonHow44/mbed,j-greffe/mbed-os,getopenmono/mbed,jeremybrodt/mbed,jferreir/mbed,mazimkhan/mbed-os,infinnovation/mbed-os,fpiot/mbed-ats,K4zuki/mbed,fpiot/mbed-ats,svogl/mbed-os,screamerbg/mbed,adamgreen/mbed,radhika-raghavendran/mbed-os5.1-onsemi,nvlsianpu/mbed,Sweet-Peas/mbed,mnlipp/mbed,netzimme/mbed-os,kpurusho/mbed,sg-/mbed-drivers,naves-thiago/mbed-midi,mbedmicro/mbed,rosterloh/mbed,mbedmicro/mbed,radhika-raghavendran/mbed-os5.1-onsemi,jeremybrodt/mbed,kl-cruz/mbed-os,struempelix/mbed,svogl/mbed-os,naves-thiago/mbed-midi,Timmmm/mbed,arostm/mbed-os,wodji/mbed,fahhem/mbed-os,Shengliang/mbed,EmuxEvans/mbed,catiedev/mbed-os,logost/mbed,nvlsianpu/mbed,infinnovation/mbed-os,fanghuaqi/mbed,mikaleppanen/mbed-os,mmorenobarm/mbed-os,rgrover/mbed,jeremybrodt/mbed,autopulated/mbed,logost/mbed,masaohamanaka/mbed,DanKupiniak/mbed,pi19404/mbed,jrjang/mbed,YarivCol/mbed-os,pradeep-gr/mbed-os5-onsemi,nRFMesh/mbed-os,xcrespo/mbed,fpiot/mbed-ats,screamerbg/mbed,bentwire/mbed,EmuxEvans/mbed,struempelix/mbed,kpurusho/mbed,adustm/mbed,infinnovation/mbed-os,nvlsianpu/mbed,adamgreen/mbed,bulislaw/mbed-os,Marcomissyou/mbed,dbestm/mbed,logost/mbed,rgrover/mbed,alertby/mbed,EmuxEvans/mbed,Tiryoh/mbed,struempelix/mbed,rosterloh/mbed,masaohamanaka/mbed,tung7970/mbed-os,adustm/mbed,ban4jp/mbed,fvincenzo/mbed-os,tung7970/mbed-os-1,jamesadevine/mbed,wodji/mbed,kjbracey-arm/mbed,JasonHow44/mbed,brstew/MBED-BUILD,adustm/mbed,fanghuaqi/mbed,adamgreen/mbed,Shengliang/mbed,catiedev/mbed-os,maximmbed/mbed,jamesadevine/mbed,andcor02/mbed-os,adustm/mbed,ARM-software/mbed-beetle,FranklyDev/mbed,logost/mbed,mnlipp/mbed,Willem23/mbed,infinnovation/mbed-os,Marcomissyou/mbed,masaohamanaka/mbed,radhika-raghavendran/mbed-os5.1-onsemi,karsev/mbed-os,catiedev/mbed-os,Timmmm/mbed,jeremybrodt/mbed,struempelix/mbed,naves-thiago/mbed-midi,NitinBhaskar/mbed,sam-geek/mbed,larks/mbed,ban4jp/mbed,Sweet-Peas/mbed,EmuxEvans/mbed,screamerbg/mbed,brstew/MBED-BUILD,ban4jp/mbed,netzimme/mbed-os,tung7970/mbed-os-1,j-greffe/mbed-os,netzimme/mbed-os,kjbracey-arm/mbed,geky/mbed,K4zuki/mbed,pbrook/mbed,0xc0170/mbed-drivers,NXPmicro/mbed,andreaslarssonublox/mbed,jamesadevine/mbed,masaohamanaka/mbed,EmuxEvans/mbed,c1728p9/mbed-os,fahhem/mbed-os,fpiot/mbed-ats,wodji/mbed,ban4jp/mbed,andcor02/mbed-os,c1728p9/mbed-os,Sweet-Peas/mbed,RonEld/mbed,mbedmicro/mbed,dbestm/mbed,fahhem/mbed-os,hwfwgrp/mbed,bulislaw/mbed-os,bikeNomad/mbed,jferreir/mbed,pedromes/mbed,wodji/mbed,theotherjimmy/mbed,tung7970/mbed-os-1,bremoran/mbed-drivers,dbestm/mbed,geky/mbed,infinnovation/mbed-os,alertby/mbed,Timmmm/mbed,CalSol/mbed,brstew/MBED-BUILD,mnlipp/mbed,ARM-software/mbed-beetle,monkiineko/mbed-os,jferreir/mbed,larks/mbed,xcrespo/mbed,Sweet-Peas/mbed,NXPmicro/mbed,screamerbg/mbed,kl-cruz/mbed-os,Shengliang/mbed,karsev/mbed-os,kl-cruz/mbed-os,geky/mbed,fahhem/mbed-os,infinnovation/mbed-os,JasonHow44/mbed,maximmbed/mbed,Timmmm/mbed,sg-/mbed-drivers,sam-geek/mbed,kl-cruz/mbed-os,pradeep-gr/mbed-os5-onsemi,K4zuki/mbed,c1728p9/mbed-os,fpiot/mbed-ats,devanlai/mbed,mazimkhan/mbed-os,larks/mbed,jrjang/mbed,geky/mbed,theotherjimmy/mbed,Timmmm/mbed,logost/mbed,monkiineko/mbed-os,NitinBhaskar/mbed,ryankurte/mbed-os,Shengliang/mbed,karsev/mbed-os,Archcady/mbed-os,FranklyDev/mbed,alertby/mbed,al177/mbed,xcrespo/mbed,theotherjimmy/mbed,Sweet-Peas/mbed,dbestm/mbed,larks/mbed,jpbrucker/mbed,autopulated/mbed,radhika-raghavendran/mbed-os5.1-onsemi,CalSol/mbed,bentwire/mbed,svastm/mbed,tung7970/mbed-os-1,fvincenzo/mbed-os,c1728p9/mbed-os,logost/mbed,betzw/mbed-os,FranklyDev/mbed,betzw/mbed-os,bulislaw/mbed-os,andreaslarssonublox/mbed,RonEld/mbed,Marcomissyou/mbed,andcor02/mbed-os,bcostm/mbed-os,adamgreen/mbed,autopulated/mbed,ryankurte/mbed-os,ryankurte/mbed-os,al177/mbed,NXPmicro/mbed,Shengliang/mbed,sam-geek/mbed,kpurusho/mbed,j-greffe/mbed-os,masaohamanaka/mbed,hwfwgrp/mbed,YarivCol/mbed-os,dbestm/mbed,tung7970/mbed-os-1,YarivCol/mbed-os,catiedev/mbed-os,getopenmono/mbed,hwfwgrp/mbed,naves-thiago/mbed-midi,brstew/MBED-BUILD,pradeep-gr/mbed-os5-onsemi,al177/mbed,GustavWi/mbed,radhika-raghavendran/mbed-os5.1-onsemi,autopulated/mbed,tung7970/mbed-os,xcrespo/mbed,kpurusho/mbed,adamgreen/mbed,Tiryoh/mbed,al177/mbed,Archcady/mbed-os,FranklyDev/mbed,RonEld/mbed,struempelix/mbed,svastm/mbed,Shengliang/mbed,fanghuaqi/mbed,arostm/mbed-os,masaohamanaka/mbed,mnlipp/mbed,xcrespo/mbed,DanKupiniak/mbed,screamerbg/mbed,fanghuaqi/mbed,adamgreen/mbed,HeadsUpDisplayInc/mbed,Willem23/mbed,Tiryoh/mbed,NXPmicro/mbed,jpbrucker/mbed,betzw/mbed-os,maximmbed/mbed,pi19404/mbed,netzimme/mbed-os,hwfwgrp/mbed,HeadsUpDisplayInc/mbed,xcrespo/mbed,bentwire/mbed,YarivCol/mbed-os,mikaleppanen/mbed-os,adustm/mbed,fanghuaqi/mbed,jrjang/mbed,catiedev/mbed-os,pbrook/mbed,getopenmono/mbed,bulislaw/mbed-os,alertby/mbed,mmorenobarm/mbed-os,JasonHow44/mbed,mmorenobarm/mbed-os,karsev/mbed-os,cvtsi2sd/mbed-os,autopulated/mbed,Archcady/mbed-os,devanlai/mbed,betzw/mbed-os,jrjang/mbed,jrjang/mbed,brstew/MBED-BUILD,maximmbed/mbed,netzimme/mbed-os,bcostm/mbed-os,GustavWi/mbed,pradeep-gr/mbed-os5-onsemi,hwfwgrp/mbed,mnlipp/mbed,nvlsianpu/mbed,al177/mbed,andcor02/mbed-os,mbedmicro/mbed,betzw/mbed-os,nvlsianpu/mbed,rosterloh/mbed,GustavWi/mbed,nRFMesh/mbed-os,mnlipp/mbed,fvincenzo/mbed-os,bulislaw/mbed-os,Timmmm/mbed,pi19404/mbed,jferreir/mbed,arostm/mbed-os,sam-geek/mbed,DanKupiniak/mbed,GustavWi/mbed,bcostm/mbed-os,getopenmono/mbed,cvtsi2sd/mbed-os,pedromes/mbed,YarivCol/mbed-os,j-greffe/mbed-os,svogl/mbed-os,mazimkhan/mbed-os,monkiineko/mbed-os,jamesadevine/mbed,bikeNomad/mbed,jamesadevine/mbed,getopenmono/mbed,arostm/mbed-os,larks/mbed,theotherjimmy/mbed,mazimkhan/mbed-os,pedromes/mbed,kl-cruz/mbed-os,jferreir/mbed,jeremybrodt/mbed,HeadsUpDisplayInc/mbed,karsev/mbed-os,iriark01/mbed-drivers,theotherjimmy/mbed,mikaleppanen/mbed-os,Tiryoh/mbed,RonEld/mbed,maximmbed/mbed,ARM-software/mbed-beetle,NitinBhaskar/mbed,FranklyDev/mbed,ryankurte/mbed-os,nvlsianpu/mbed,c1728p9/mbed-os,CalSol/mbed,tung7970/mbed-os,Marcomissyou/mbed,kpurusho/mbed,mbedmicro/mbed,devanlai/mbed,Willem23/mbed,jrjang/mbed,rosterloh/mbed,brstew/MBED-BUILD,devanlai/mbed,mmorenobarm/mbed-os,geky/mbed,RonEld/mbed,0xc0170/mbed-drivers,mazimkhan/mbed-os,mikaleppanen/mbed-os,nRFMesh/mbed-os,CalSol/mbed,K4zuki/mbed,autopulated/mbed,jpbrucker/mbed,struempelix/mbed,pi19404/mbed,dbestm/mbed,svogl/mbed-os,kpurusho/mbed,adustm/mbed,al177/mbed,monkiineko/mbed-os,pradeep-gr/mbed-os5-onsemi,CalSol/mbed,andreaslarssonublox/mbed,nRFMesh/mbed-os,pi19404/mbed,getopenmono/mbed,nabilbendafi/mbed,ban4jp/mbed,tung7970/mbed-os,j-greffe/mbed-os