Bug 1015247 - [Music] Update to use gaia-header

Just now I found an AVRCP regression in music app which caused by the launch_patch, in https://bugzilla.mozilla.org/show_bug.cgi?id=1050112, so if that patch lands, we should also change the media-button path to the lauch_patch, that means they should be exactly the same, or we will lose AVRCP again.