AVRCP: Make artist metadata come from ARTIST and fallback to ALBUMARTIST

Makes artist appear on bluetooth device when music player only sents
artist (Apollo does this)

Change-Id: I75ca5515d0f20fc647e8d55a339610a7d5dbeba1
Send out a broadcast intent when BT voice dialing is shut down.

This broadcast can be used by voice dialing applications to stop
themselves.

Change-Id: Ia9f5b6bc4cbfd18bddc40f98170463b613a9c329