Telephony: Dismissable voicemail notifications

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

Change-Id: Iccd01210cdd9a43167392fc09debbfc4cb23b6f6

Conflicts:
	src/com/android/phone/NotificationMgr.java
Merge pull request #1 from AOSPA-legacy/kitkat

Telephony: Dismissable voicemail notifications