Add center clock [1/2]

Conflicts:
	core/java/android/provider/Settings.java
	packages/SystemUI/res/layout/status_bar.xml
	packages/SystemUI/res/layout/status_bar_expanded_header.xml
	packages/SystemUI/src/com/android/systemui/statusbar/phone/PhoneStatusBar.java
	packages/SystemUI/src/com/android/systemui/statusbar/policy/Clock.java
	packages/SystemUI/src/com/android/systemui/statusbar/tablet/TabletStatusBar.java