Launch music player on headset connect

Launches the default music player when a headset is connected

Patchset 2 - Add headset category
Patchset 3 - Remove summary

Change-Id: I1ee973bec35d95285a646b86213ced3dd15852ed

Conflicts:

	res/values/strings.xml
	src/com/android/settings/SoundSettings.java