mjpeg-player: make the player reload m3u playlists that are live.

In hls.js, the level contoller (in level-contoller.js) is responsible for reloading m3u playlists. This functionality needs to be added to our play in order to playback a livestream.

The files, level-controller.js and level-helper.js should be adapted to work with our player. Also when a Hls object is created, it should have a LevelController object associated, (this needs to be added in hls.js).