Added configuration mechanism
Added configuration mechanism

If the build system finds a file named mbed_config.h, it will automatically
define a HAVE_MBED_CONFIG_H macro. Various libraries/components can use
this mechanism to provide compile-time configuration for user projects.

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