Merge pull request #6031 from MichelRottleuthner/sdcard_spi_testing

boards/remote-revb/include/board.h

drivers/Makefile.dep

drivers/Makefile.include

drivers/include/sdcard_spi.h

drivers/sdcard_spi/Makefile

drivers/sdcard_spi/include/sdcard_spi_internal.h

drivers/sdcard_spi/include/sdcard_spi_params.h

drivers/sdcard_spi/sdcard_spi.c

sys/auto_init/Makefile

sys/auto_init/auto_init.c

sys/auto_init/storage/Makefile

sys/auto_init/storage/auto_init_sdcard_spi.c

tests/driver_sdcard_spi/Makefile

tests/driver_sdcard_spi/main.c