Allow ogg files to be selected as ringtones

Bug: 37891455
Test: manual - open custom phone ringtone picker in settings, navigate
to an .ogg file, and it should be selectable; select it and it should
add itself to the list of available ringtones, and play its sample
correctly.

Change-Id: I33b1ff07d0b43646c807ba0994efa4f6d8d95cae