SystemUI: Separate system bar BGs for themes

This commit separates the navigation bar background colors from the
status bar background colors which allows more modular theme-ability.
Backwards compatibility for the old system bar values is still
preserved, but the new values are to be prioritized.

Thanks to Arz Bhatia for the suggestion.

Change-Id: Ibe579d16ea35ca5bdcfe9f98143c3f91cd24900f

Conflicts:
	packages/SystemUI/res/values/cm_colors.xml
	packages/SystemUI/src/com/android/systemui/statusbar/phone/BarTransitions.java
	packages/SystemUI/src/com/android/systemui/statusbar/phone/NavigationBarTransitions.java
	packages/SystemUI/src/com/android/systemui/statusbar/phone/PhoneStatusBarTransitions.java
Fix

Change-Id: I368e36ce206b6dd6a0ca5f62c2ac0d988ffdde61
SettingsProvider: Update icon.

Change-Id: I9e1b540e0268643371dd95593eaefa63d4a1827d