Revert "NavigationBar : Customization"

This reverts commit ad97960bd783da565bb022724165d2d695656786.

Change-Id: If459190064ba8b17aec3ce19eb363ec07bd1e1e6

Conflicts:
	packages/SystemUI/res/layout/navigation_bar.xml
	packages/SystemUI/src/com/android/systemui/statusbar/phone/NavigationBarView.java
	packages/SystemUI/src/com/android/systemui/statusbar/phone/PhoneStatusBar.java
	packages/SystemUI/src/com/android/systemui/statusbar/policy/KeyButtonView.java