Pull accelerometer clean

In this pull request I add a fallback solution and some other additional development. if rotation vector is not provided then will be used accelerometer sensor.

If the Android device is not contain rotation vector sensor or accelerometer sensor then the gyroscope controller option is not will be available in the preference settings (and will be unchecked).

In the getPitch and getRoll functions now will handle the overshoots of the max roll/pitch angle.

Fix the stucked flightdata on UI after disable.

Will be disabled the controller after onPause()

The reason of the sensors fallback solution is that lot of devices is not support the rotation vector sensor because it depend from Accelerometer, Gyroscope and Magnetometer (maybe except the gyroscope). https://source.android.com/devices/sensors/composite_sensors.html