Merge pull request #4699 from gebart/pr/makefile-reorganize

Makefile

Makefile.include

boards/airfy-beacon/Makefile.include

boards/arduino-due/Makefile.include

boards/arduino-zero/Makefile.include

boards/calliope-mini/Makefile.include

boards/cc2538dk/Makefile.include

boards/cc2650stk/Makefile.include

boards/ek-lm4f120xl/Makefile.include

boards/f4vi1/Makefile.include

boards/fox/Makefile.include

boards/frdm-k64f/Makefile.include

boards/iotlab-common/Makefile.include

boards/limifrog-v1/Makefile.include

boards/maple-mini/Makefile.include

boards/mbed_lpc1768/Makefile.include

boards/microbit/Makefile.include

boards/msb-430-common/Makefile.include

boards/msbiot/Makefile.include

boards/mulle/Makefile.include