SystemUi: Custom Navigation Ring

This Allows up to 3 targets on the navigation ring
with custom actions.

Change-Id: Ic5bc6021d55b9c266527463bb916283feb00ad06

Conflicts:

	core/java/android/provider/Settings.java
	core/res/res/values/symbols.xml

Conflicts:

	core/res/res/values/symbols.xml