Update README
Update README

Changed OS X build instructions to force qmake to generate a Makefile instead of xcodeproj files.
RedoXyde/PX4_qGCS,devbharat/qgroundcontrol,scott-eddy/qgroundcontrol,BMP-TECH/qgroundcontrol,LIKAIMO/qgroundcontrol,mirkix/apm_planner,catch-twenty-two/qgroundcontrol,lis-epfl/qgroundcontrol,scott-eddy/qgroundcontrol,jy723/qgroundcontrol,TheIronBorn/qgroundcontrol,chen0510566/apm_planner,devbharat/qgroundcontrol,Hunter522/qgroundcontrol,dcarpy/apm_planner,TheIronBorn/qgroundcontrol,caoxiongkun/qgroundcontrol,hejunbok/qgroundcontrol,WorkerBees/apm_planner,labtoast/apm_planner,fizzaly/qgroundcontrol,jy723/qgroundcontrol,nado1688/qgroundcontrol,jy723/qgroundcontrol,mihadyuk/qgroundcontrol,UAVenture/qgroundcontrol,kellyschrock/apm_planner,xros/apm_planner,mrpilot2/apm_planner,kd0aij/qgroundcontrol,ethz-asl/qgc_asl,fizzaly/qgroundcontrol,Icenowy/apm_planner,LIKAIMO/qgroundcontrol,hejunbok/apm_planner,catch-twenty-two/qgroundcontrol,WorkerBees/apm_planner,BMP-TECH/qgroundcontrol,remspoor/qgroundcontrol,LIKAIMO/apm_planner,scott-eddy/qgroundcontrol,CornerOfSkyline/qgroundcontrol,caoxiongkun/qgroundcontrol,chen0510566/apm_planner,duststorm/apm_planner,Icenowy/apm_planner,LittleBun/apm_planner,LIKAIMO/apm_planner,fizzaly/qgroundcontrol,ethz-asl/qgc_asl,LIKAIMO/qgroundcontrol,ethz-asl/qgc_asl,381426068/apm_planner,labtoast/apm_planner,BMP-TECH/qgroundcontrol,catch-twenty-two/qgroundcontrol,fizzaly/qgroundcontrol,caoxiongkun/qgroundcontrol,xros/apm_planner,josephlewis42/UDenverQGC2,xros/apm_planner,cfelipesouza/qgroundcontrol,sverling/qgc_asl,LIKAIMO/apm_planner,iidioter/qgroundcontrol,devbharat/qgroundcontrol,CornerOfSkyline/qgroundcontrol,duststorm/apm_planner,nado1688/qgroundcontrol,Icenowy/apm_planner,remspoor/qgroundcontrol,greenoaktree/qgroundcontrol,duststorm/apm_planner,LittleBun/apm_planner,CornerOfSkyline/qgroundcontrol,TheIronBorn/qgroundcontrol,kellyschrock/apm_planner,dagoodma/qgroundcontrol,CornerOfSkyline/qgroundcontrol,LIKAIMO/apm_planner,sverling/qgc_asl,mrpilot2/apm_planner,mrpilot2/apm_planner,kd0aij/qgroundcontrol,iidioter/qgroundcontrol,kellyschrock/apm_planner,remspoor/qgroundcontrol,gpaes/apm_planner,hejunbok/apm_planner,josephlewis42/UDenverQGC2,dcarpy/apm_planner,abcdelf/apm_planner,sutherlandm/apm_planner,chen0510566/apm_planner,dcarpy/apm_planner,chen0510566/apm_planner,duststorm/apm_planner,Hunter522/qgroundcontrol,hejunbok/qgroundcontrol,labtoast/apm_planner,diydrones/apm_planner,mirkix/apm_planner,lis-epfl/qgroundcontrol,cfelipesouza/qgroundcontrol,381426068/apm_planner,mihadyuk/qgroundcontrol,cfelipesouza/qgroundcontrol,Hunter522/qgroundcontrol,xros/apm_planner,josephlewis42/UDenverQGC2,iidioter/qgroundcontrol,TheIronBorn/qgroundcontrol,lis-epfl/qgroundcontrol,gpaes/apm_planner,abcdelf/apm_planner,LittleBun/apm_planner,ethz-asl/qgc_asl,jy723/qgroundcontrol,Icenowy/apm_planner,hejunbok/qgroundcontrol,cfelipesouza/qgroundcontrol,hejunbok/apm_planner,hejunbok/apm_planner,caoxiongkun/qgroundcontrol,greenoaktree/qgroundcontrol,LIKAIMO/qgroundcontrol,chen0510566/apm_planner,duststorm/apm_planner,nado1688/qgroundcontrol,gpaes/apm_planner,dcarpy/apm_planner,greenoaktree/qgroundcontrol,mirkix/apm_planner,Icenowy/apm_planner,LIKAIMO/qgroundcontrol,sverling/qgc_asl,scott-eddy/qgroundcontrol,LittleBun/apm_planner,abcdelf/apm_planner,sverling/qgc_asl,scott-eddy/qgroundcontrol,remspoor/qgroundcontrol,labtoast/apm_planner,mirkix/apm_planner,iidioter/qgroundcontrol,sutherlandm/apm_planner,diydrones/apm_planner,Hunter522/qgroundcontrol,LittleBun/apm_planner,CornerOfSkyline/qgroundcontrol,mirkix/apm_planner,dcarpy/apm_planner,hejunbok/qgroundcontrol,greenoaktree/qgroundcontrol,sutherlandm/apm_planner,UAVenture/qgroundcontrol,Hunter522/qgroundcontrol,gpaes/apm_planner,josephlewis42/UDenverQGC2,381426068/apm_planner,sutherlandm/apm_planner,BMP-TECH/qgroundcontrol,remspoor/qgroundcontrol,BMP-TECH/qgroundcontrol,dagoodma/qgroundcontrol,kd0aij/qgroundcontrol,cfelipesouza/qgroundcontrol,dagoodma/qgroundcontrol,kellyschrock/apm_planner,diydrones/apm_planner,mihadyuk/qgroundcontrol,LIKAIMO/qgroundcontrol,TheIronBorn/qgroundcontrol,dagoodma/qgroundcontrol,381426068/apm_planner,BMP-TECH/qgroundcontrol,kd0aij/qgroundcontrol,UAVenture/qgroundcontrol,kellyschrock/apm_planner,UAVenture/qgroundcontrol,RedoXyde/PX4_qGCS,jy723/qgroundcontrol,dcarpy/apm_planner,mirkix/apm_planner,Hunter522/qgroundcontrol,xros/apm_planner,gpaes/apm_planner,remspoor/qgroundcontrol,catch-twenty-two/qgroundcontrol,iidioter/qgroundcontrol,381426068/apm_planner,gpaes/apm_planner,lis-epfl/qgroundcontrol,duststorm/apm_planner,RedoXyde/PX4_qGCS,jy723/qgroundcontrol,diydrones/apm_planner,devbharat/qgroundcontrol,abcdelf/apm_planner,devbharat/qgroundcontrol,scott-eddy/qgroundcontrol,mrpilot2/apm_planner,381426068/apm_planner,catch-twenty-two/qgroundcontrol,nado1688/qgroundcontrol,kellyschrock/apm_planner,hejunbok/apm_planner,RedoXyde/PX4_qGCS,RedoXyde/PX4_qGCS,catch-twenty-two/qgroundcontrol,abcdelf/apm_planner,mihadyuk/qgroundcontrol,iidioter/qgroundcontrol,labtoast/apm_planner,kd0aij/qgroundcontrol,RedoXyde/PX4_qGCS,sutherlandm/apm_planner,ethz-asl/qgc_asl,LittleBun/apm_planner,LIKAIMO/apm_planner,CornerOfSkyline/qgroundcontrol,dagoodma/qgroundcontrol,dagoodma/qgroundcontrol,fizzaly/qgroundcontrol,mihadyuk/qgroundcontrol,greenoaktree/qgroundcontrol,sverling/qgc_asl,UAVenture/qgroundcontrol,Icenowy/apm_planner,LIKAIMO/apm_planner,labtoast/apm_planner,xros/apm_planner,lis-epfl/qgroundcontrol,hejunbok/qgroundcontrol,nado1688/qgroundcontrol,TheIronBorn/qgroundcontrol,fizzaly/qgroundcontrol,mrpilot2/apm_planner,caoxiongkun/qgroundcontrol,hejunbok/apm_planner,hejunbok/qgroundcontrol,abcdelf/apm_planner,sutherlandm/apm_planner,caoxiongkun/qgroundcontrol,WorkerBees/apm_planner,devbharat/qgroundcontrol,diydrones/apm_planner,chen0510566/apm_planner,WorkerBees/apm_planner,kd0aij/qgroundcontrol,cfelipesouza/qgroundcontrol,greenoaktree/qgroundcontrol,nado1688/qgroundcontrol,diydrones/apm_planner,mihadyuk/qgroundcontrol,UAVenture/qgroundcontrol,mrpilot2/apm_planner