Phone notification LED settings backend
Cleanup: get rid of getCurrentCall() method.

The only caller was the vibration code, which only used it when the call is picked up. As a picked up call is always the foreground one, we can safely just use that.
Fix 'vibrate outgoing' behaviour.
Telephony: Dismissable voicemail notifications

Ported from cm-10.2:
http://review.cyanogenmod.org/#/c/35023

Change-Id: Iccd01210cdd9a43167392fc09debbfc4cb23b6f6