Merge remote-tracking branch 'origin/edge' into feature/new_build

Merge remote-tracking branch 'origin/edge' into feature/new_build

Conflicts:
	.gitignore
	build/mbed_custom.c
	gcc4mbed/build/gcc4mbed.mk
	makefile
	mbed/src/vendor/NXP/cmsis/LPC1768/GCC_ARM/LPC1768.ld

Fixed conflicts caused by heap tagging commit which modified several
files that had been moved around for this new build system.

NOTE: HEAP_TAGS has been disabled since it isn't compatible with newlib
      nano.  If we decide that we want to stay with newlib nano then I
      can update the heap tag code to work with this newer library.