Adding Android Sensor support as simulated joysticks. Only orientation is supported...

Adding Android Sensor support as simulated joysticks.  Only orientation is supported right now, more sensor types to be added later.  When device orientation changes, Joystick[0] is updated just like using an actual joystick.  Users need to add "joystickEventsEnabled = true" to the MainActivity to enable the orientation joystick so battery life is conserved if sensor data is not desired.  See jmonkeyengine.org/groups/android/forum/topic/creating-engine-support-for-android-sensor-input/ for the long history.

git-svn-id: http://jmonkeyengine.googlecode.com/svn/trunk@9700 75d07b2b-3a1a-0410-a2c5-0572b91ccdca