SystemUI: add signal text (1/2)

PS9:
 - default colors to white
 - use PhoneStateListener instead of deprecated implementation
 - removed unused code

PS11: Fix build error

Change-Id: I96fe28fdf946e1372ec4dd8df3adae4aece4b509

Conflicts:
	core/java/android/provider/Settings.java
	packages/SystemUI/res/layout/signal_cluster_view.xml
	packages/SystemUI/src/com/android/systemui/statusbar/SignalClusterView.java