Merge pull request #6082 from haukepetersen/add_board_microbit

boards/microbit/Makefile

boards/microbit/Makefile.dep

boards/microbit/Makefile.features

boards/microbit/Makefile.include

boards/microbit/board.c

boards/microbit/dist/flash.sh

boards/microbit/include/board.h

boards/microbit/include/gpio_params.h

boards/microbit/include/microbit.h

boards/microbit/include/periph_conf.h

boards/microbit/microbit/Makefile

boards/microbit/microbit/microbit.c

examples/dtls-echo/Makefile

examples/gnrc_border_router/Makefile

examples/gnrc_networking/Makefile

examples/gnrc_tftp/Makefile

examples/microcoap_server/Makefile

sys/include/mineplex.h

sys/mineplex/Makefile

sys/mineplex/mineplex.c