Changed the envvar name to MICROPY_MICROPYTHON
Changed the envvar name to MICROPY_MICROPYTHON

As discussed in #504
feilongfl/micropython,mgyenik/micropython,kerneltask/micropython,adafruit/micropython,firstval/micropython,torwag/micropython,PappaPeppar/micropython,deshipu/micropython,Timmenem/micropython,SHA2017-badge/micropython-esp32,tuc-osg/micropython,ganshun666/micropython,tuc-osg/micropython,MrSurly/micropython,emfcamp/micropython,SHA2017-badge/micropython-esp32,drrk/micropython,PappaPeppar/micropython,neilh10/micropython,aethaniel/micropython,mhoffma/micropython,danicampora/micropython,martinribelotta/micropython,redbear/micropython,selste/micropython,misterdanb/micropython,AriZuu/micropython,Vogtinator/micropython,martinribelotta/micropython,mhoffma/micropython,turbinenreiter/micropython,alex-robbins/micropython,skybird6672/micropython,blazewicz/micropython,rubencabrera/micropython,trezor/micropython,HenrikSolver/micropython,lbattraw/micropython,xhat/micropython,praemdonck/micropython,ryannathans/micropython,PappaPeppar/micropython,firstval/micropython,redbear/micropython,dinau/micropython,paul-xxx/micropython,tobbad/micropython,cwyark/micropython,neilh10/micropython,pozetroninc/micropython,adamkh/micropython,toolmacher/micropython,hosaka/micropython,slzatz/micropython,xuxiaoxin/micropython,Vogtinator/micropython,danicampora/micropython,misterdanb/micropython,cloudformdesign/micropython,adafruit/circuitpython,mianos/micropython,trezor/micropython,ahotam/micropython,mpalomer/micropython,tdautc19841202/micropython,heisewangluo/micropython,cwyark/micropython,chrisdearman/micropython,suda/micropython,dinau/micropython,torwag/micropython,infinnovation/micropython,swegener/micropython,KISSMonX/micropython,kerneltask/micropython,cnoviello/micropython,dinau/micropython,vitiral/micropython,slzatz/micropython,mianos/micropython,Timmenem/micropython,lbattraw/micropython,mianos/micropython,pramasoul/micropython,Peetz0r/micropython-esp32,hosaka/micropython,adafruit/circuitpython,matthewelse/micropython,TDAbboud/micropython,ceramos/micropython,adafruit/micropython,mgyenik/micropython,emfcamp/micropython,bvernoux/micropython,ericsnowcurrently/micropython,dinau/micropython,skybird6672/micropython,tobbad/micropython,dxxb/micropython,martinribelotta/micropython,AriZuu/micropython,suda/micropython,suda/micropython,galenhz/micropython,ChuckM/micropython,cwyark/micropython,jimkmc/micropython,toolmacher/micropython,SungEun-Steve-Kim/test-mp,xyb/micropython,rubencabrera/micropython,xyb/micropython,omtinez/micropython,mgyenik/micropython,hiway/micropython,torwag/micropython,jlillest/micropython,ChuckM/micropython,tdautc19841202/micropython,puuu/micropython,firstval/micropython,stonegithubs/micropython,noahwilliamsson/micropython,suda/micropython,heisewangluo/micropython,ruffy91/micropython,EcmaXp/micropython,cnoviello/micropython,supergis/micropython,AriZuu/micropython,tdautc19841202/micropython,orionrobots/micropython,aethaniel/micropython,slzatz/micropython,KISSMonX/micropython,xuxiaoxin/micropython,warner83/micropython,ceramos/micropython,SHA2017-badge/micropython-esp32,jlillest/micropython,adafruit/circuitpython,EcmaXp/micropython,oopy/micropython,ganshun666/micropython,blazewicz/micropython,SHA2017-badge/micropython-esp32,micropython/micropython-esp32,pramasoul/micropython,martinribelotta/micropython,vriera/micropython,MrSurly/micropython-esp32,drrk/micropython,deshipu/micropython,henriknelson/micropython,galenhz/micropython,vriera/micropython,mgyenik/micropython,blazewicz/micropython,tuc-osg/micropython,pfalcon/micropython,micropython/micropython-esp32,kostyll/micropython,TDAbboud/micropython,vriera/micropython,Timmenem/micropython,orionrobots/micropython,ruffy91/micropython,noahchense/micropython,toolmacher/micropython,HenrikSolver/micropython,ahotam/micropython,adamkh/micropython,Vogtinator/micropython,blmorris/micropython,methoxid/micropystat,AriZuu/micropython,alex-march/micropython,paul-xxx/micropython,jmarcelino/pycom-micropython,tdautc19841202/micropython,xyb/micropython,galenhz/micropython,dmazzella/micropython,MrSurly/micropython-esp32,chrisdearman/micropython,supergis/micropython,pozetroninc/micropython,ahotam/micropython,drrk/micropython,tralamazza/micropython,tobbad/micropython,neilh10/micropython,mhoffma/micropython,mpalomer/micropython,adamkh/micropython,KISSMonX/micropython,alex-march/micropython,xuxiaoxin/micropython,xyb/micropython,blmorris/micropython,danicampora/micropython,infinnovation/micropython,EcmaXp/micropython,alex-robbins/micropython,mpalomer/micropython,puuu/micropython,pfalcon/micropython,jmarcelino/pycom-micropython,ernesto-g/micropython,methoxid/micropystat,skybird6672/micropython,warner83/micropython,stonegithubs/micropython,ruffy91/micropython,vitiral/micropython,warner83/micropython,PappaPeppar/micropython,TDAbboud/micropython,lbattraw/micropython,cloudformdesign/micropython,tralamazza/micropython,jlillest/micropython,dmazzella/micropython,EcmaXp/micropython,MrSurly/micropython,dhylands/micropython,martinribelotta/micropython,ernesto-g/micropython,redbear/micropython,KISSMonX/micropython,oopy/micropython,ganshun666/micropython,aethaniel/micropython,MrSurly/micropython,feilongfl/micropython,oopy/micropython,jlillest/micropython,jimkmc/micropython,ahotam/micropython,paul-xxx/micropython,tralamazza/micropython,ahotam/micropython,utopiaprince/micropython,dmazzella/micropython,deshipu/micropython,dxxb/micropython,ryannathans/micropython,mianos/micropython,noahchense/micropython,pramasoul/micropython,infinnovation/micropython,TDAbboud/micropython,rubencabrera/micropython,danicampora/micropython,mhoffma/micropython,lowRISC/micropython,ganshun666/micropython,kostyll/micropython,dinau/micropython,puuu/micropython,Timmenem/micropython,ceramos/micropython,orionrobots/micropython,stonegithubs/micropython,emfcamp/micropython,tobbad/micropython,kostyll/micropython,blmorris/micropython,jimkmc/micropython,matthewelse/micropython,feilongfl/micropython,lbattraw/micropython,misterdanb/micropython,MrSurly/micropython-esp32,hosaka/micropython,lowRISC/micropython,stonegithubs/micropython,adafruit/circuitpython,turbinenreiter/micropython,aethaniel/micropython,praemdonck/micropython,xhat/micropython,MrSurly/micropython-esp32,skybird6672/micropython,dhylands/micropython,micropython/micropython-esp32,bvernoux/micropython,matthewelse/micropython,selste/micropython,ceramos/micropython,MrSurly/micropython-esp32,ryannathans/micropython,heisewangluo/micropython,tuc-osg/micropython,emfcamp/micropython,toolmacher/micropython,supergis/micropython,ernesto-g/micropython,selste/micropython,deshipu/micropython,matthewelse/micropython,SHA2017-badge/micropython-esp32,dhylands/micropython,toolmacher/micropython,galenhz/micropython,SungEun-Steve-Kim/test-mp,ericsnowcurrently/micropython,adamkh/micropython,dhylands/micropython,Peetz0r/micropython-esp32,hiway/micropython,ruffy91/micropython,mgyenik/micropython,micropython/micropython-esp32,HenrikSolver/micropython,hiway/micropython,ericsnowcurrently/micropython,noahwilliamsson/micropython,dxxb/micropython,PappaPeppar/micropython,noahwilliamsson/micropython,kerneltask/micropython,omtinez/micropython,tuc-osg/micropython,noahchense/micropython,TDAbboud/micropython,omtinez/micropython,slzatz/micropython,firstval/micropython,adamkh/micropython,MrSurly/micropython,trezor/micropython,ChuckM/micropython,swegener/micropython,hosaka/micropython,omtinez/micropython,turbinenreiter/micropython,EcmaXp/micropython,Peetz0r/micropython-esp32,cloudformdesign/micropython,trezor/micropython,praemdonck/micropython,feilongfl/micropython,cwyark/micropython,mpalomer/micropython,drrk/micropython,lowRISC/micropython,aethaniel/micropython,AriZuu/micropython,henriknelson/micropython,mhoffma/micropython,henriknelson/micropython,utopiaprince/micropython,kostyll/micropython,ceramos/micropython,swegener/micropython,rubencabrera/micropython,alex-robbins/micropython,vriera/micropython,supergis/micropython,praemdonck/micropython,cloudformdesign/micropython,heisewangluo/micropython,torwag/micropython,cwyark/micropython,adafruit/circuitpython,blmorris/micropython,neilh10/micropython,rubencabrera/micropython,lowRISC/micropython,ryannathans/micropython,paul-xxx/micropython,cloudformdesign/micropython,chrisdearman/micropython,mpalomer/micropython,oopy/micropython,Peetz0r/micropython-esp32,HenrikSolver/micropython,jmarcelino/pycom-micropython,xhat/micropython,vitiral/micropython,HenrikSolver/micropython,emfcamp/micropython,turbinenreiter/micropython,redbear/micropython,paul-xxx/micropython,pfalcon/micropython,xuxiaoxin/micropython,dmazzella/micropython,misterdanb/micropython,bvernoux/micropython,kerneltask/micropython,bvernoux/micropython,cnoviello/micropython,ganshun666/micropython,jlillest/micropython,hosaka/micropython,SungEun-Steve-Kim/test-mp,utopiaprince/micropython,blazewicz/micropython,noahchense/micropython,infinnovation/micropython,henriknelson/micropython,feilongfl/micropython,noahchense/micropython,methoxid/micropystat,henriknelson/micropython,pozetroninc/micropython,Timmenem/micropython,noahwilliamsson/micropython,hiway/micropython,noahwilliamsson/micropython,micropython/micropython-esp32,KISSMonX/micropython,pozetroninc/micropython,alex-robbins/micropython,dxxb/micropython,adafruit/circuitpython,methoxid/micropystat,warner83/micropython,SungEun-Steve-Kim/test-mp,swegener/micropython,pozetroninc/micropython,chrisdearman/micropython,ernesto-g/micropython,Vogtinator/micropython,heisewangluo/micropython,supergis/micropython,matthewelse/micropython,jmarcelino/pycom-micropython,Vogtinator/micropython,oopy/micropython,methoxid/micropystat,xhat/micropython,puuu/micropython,bvernoux/micropython,jimkmc/micropython,pramasoul/micropython,adafruit/micropython,ChuckM/micropython,cnoviello/micropython,hiway/micropython,adafruit/micropython,danicampora/micropython,selste/micropython,pfalcon/micropython,mianos/micropython,drrk/micropython,alex-march/micropython,firstval/micropython,skybird6672/micropython,neilh10/micropython,misterdanb/micropython,xyb/micropython,ernesto-g/micropython,chrisdearman/micropython,lbattraw/micropython,tobbad/micropython,pramasoul/micropython,tdautc19841202/micropython,stonegithubs/micropython,puuu/micropython,adafruit/micropython,deshipu/micropython,omtinez/micropython,swegener/micropython,ChuckM/micropython,kerneltask/micropython,dxxb/micropython,infinnovation/micropython,praemdonck/micropython,slzatz/micropython,vriera/micropython,warner83/micropython,trezor/micropython,suda/micropython,ruffy91/micropython,xhat/micropython,orionrobots/micropython,galenhz/micropython,blazewicz/micropython,dhylands/micropython,jimkmc/micropython,pfalcon/micropython,orionrobots/micropython,alex-robbins/micropython,matthewelse/micropython,utopiaprince/micropython,ericsnowcurrently/micropython,lowRISC/micropython,jmarcelino/pycom-micropython,ericsnowcurrently/micropython,redbear/micropython,turbinenreiter/micropython,tralamazza/micropython,alex-march/micropython,kostyll/micropython,blmorris/micropython,vitiral/micropython,alex-march/micropython,xuxiaoxin/micropython,cnoviello/micropython,torwag/micropython,ryannathans/micropython,SungEun-Steve-Kim/test-mp,vitiral/micropython,selste/micropython,MrSurly/micropython,utopiaprince/micropython,Peetz0r/micropython-esp32