Add libsuperuser from chainfire
Integrate libsuperuser to AirplaneMode
Update Manifest with new version, min version and superuser permission
Update application :
* Separate airplane mode/sound off
* Update UI
* Update preference management
Update README.md
Disable AirPlane if SDK > 4.3 and su not enabled
Fix mistakes in AirplaneMode

Source code formatting
Change android version for using SU (minimum 4.2)