SystemUi: Navigation bar Quick launch shortcuts (2 of 2)

This allows up to 3 targets on the Navigation bar ring
or Home buttons with custom Quick launch shortcut actions.

Patchset 1 - 21 - Initial commits and edits
Patchset 22 - Update commit message

Change-Id: Ic5bc6021d55b9c266527463bb916283feb00ad06

Conflicts:
	core/java/android/provider/Settings.java