Merge branch 'multiwii-master'

Conflicts:
	src/board.h
	src/buzzer.c
	src/config.c
	src/drivers/serial_common.h
	src/drivers/system_common.c
	src/drv_gpio.h
	src/drv_pwm.c
	src/drv_timer.c
	src/drv_uart.c
	src/flight_imu.c
	src/mw.c
	src/rx_sbus.c
	src/sensors.c
	src/serial_cli.c
CHEBUZZF3 - Implement ADC driver for 3 ADC channels.  Use STM32F3 linker
script so it uses the right values for RAM and FLASH size.
Disable L3GD20 debug output.
Update battery voltage calculation to use a hex value for the 12bit ADC
value.