[ardrone2_raw] Battery readout for ARDrone2 RAW version. Formula to convert from 10bit ADC value to battery voltage can be improved
[boards] ardone2: correct voltage scale, thx Eric
[peripherals] updates to l3g4200 gyro from Eduardo
[imu] new GL1 driver from Eduardo

IMU from Goodluckbuy with L3G4200, ADXL345 and HMC5883.