Option to use volume keys to control media volume anytime (2/2)

See Settings part for description

Change-Id: I78d26b0bd41f5b58514ae9c68208a8c950396823

Conflicts:
	core/java/android/provider/Settings.java
	media/java/android/media/AudioService.java
Fix Logical error

Change-Id: I0b07ea92cd9b747772bf1c2376a6a801d524b7d0
Add CUSTOM_NOTIFICATION to ContactsContract to allow custom notification sounds to be assigned to individual contacts.

Change-Id: Iba40e5237200385a467ac9cdb441b1ed7de3a1da