Navigation bar dimensions (1/2)

- Change height when in portrait
- Change width when in landscape
- Option to enable or disable nav bar

This is partially ported from SlimRoms
Thanks to @kufikugel

Change-Id: Ic2bfb32684c3d74062d123266db1516e09d92fb6

Conflicts:
	policy/src/com/android/internal/policy/impl/PhoneWindowManager.java

Conflicts:
	policy/src/com/android/internal/policy/impl/PhoneWindowManager.java