Add driver and usage for LPS331AP digital barometer.
	modified:   modules/Altitude/revolution/altitude.c
	modified:   modules/Sensors/sensors.c
	new file:   pios/common/pios_lps331ap.c
	new file:   pios/inc/pios_lps331ap.h
	modified:   pios/pios.h
	modified:   targets/boards/brainyfly/firmware/inc/pios_config.h
	modified:   targets/boards/brainyfly/pios_board.h
	modified:   ../make/apps-defs.mk