Frameworks: Transparent navbar and more (1/2)

This commit introduces transparent navigation bar. Also colorizing method
changed.

- custom transparency
- custom color
- custom transparency mode (linked with statusbar transparency mode)
  0 = launcher, 1 = launcher and lockscreen, 2 = always
- Settings fits now with new functions

Patchset 2:
- cleanup some imports

cheers

Change-Id: I8df71c051b84eed8ea9db2f51f4a9d4797d3d0b9

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