InCallUI: Heads up meets SlimKat....SlimKat meets Google IO [2/4]

Add native heads up support on dialer.

We only have show call in background feature. We combine it now with heads up.
So it is doing exactly same like on Google IO was shown.

Enabled by default.

- Notification is expanded by default
- Send as requested to force show the heads up no matter what.

Change-Id: I819316226f990058e6da6c289b8424d80ac1456e

Conflicts:
	src/com/android/incallui/StatusBarNotifier.java