[1/2] Base: NavigationBar Customization

- Allows user to customize navigation bar.
  Features :
   * Choose from 1-6 # of buttons
   * Re-arrange / assign buttons

- Navbar : Rework logic for determining orientation

PS2: Add DeviceUtils helper class from slimroms
PS3: fix NavigationBarView && add lockCurrentOrientation function to DeviceUtils
(related to NavBar.java in settings)

Change-Id: Ifea7efdfe1374e71e617a113624c265938a524aa

Conflicts:
	core/java/android/provider/Settings.java
	packages/SystemUI/res/values/pa_strings.xml
	packages/SystemUI/src/com/android/systemui/statusbar/phone/NavigationBarView.java