bugfixes
- buffer-controller: flush any waiting segments on MEDIA_DETACHING
fix loop of media decode error on audio codec switch with http://www.dailymotion.com/video/x4snq9f Firefox - stream-controller: in case first frag is already loaded, restart loading in IDLE state. this is to avoid restarting in hls.startLevel (instead it will restart in hls.nextAutoLevel if auto switch is enabled