Bluetooth: Added AVRCP1.3 intents in mediaplayer.

Added posting of Metadata Changed intents to BluetoothA2dpService
for updating MediaPlayer status like STOP, PAUSE, PLAY, FWD_SEEK,
REV_SEEK along with metadata of the current song.

Change-Id: I47bbea35c982d07fecdbb9245cc48af58fb1d78a
CRs-fixed: 443134

Conflicts:
	media/java/android/media/MediaPlayer.java