Replace JW Player with mediaelement.js for playing video and audio

The JW Player we use is outdated but can't be updated because the the player needs to be relatively installed to the document base. This is not useful in our case as the base URL differs in content but the player is always at the same location.

Thus, the video player should be replaced with the jQuery player jPlayer (http://jplayer.org) or another alternative.

To support youtube the player wrapper is extended to embed the standard youtube player in such a case.

After some discussions and experiments we tend towards implementing http://mediaelementjs.com

• rtmp support (needs to be confirmed)
• m3u8 / HLS on Akamay supported (tested)
• mp4 etc
• YouTube plugin available
• loading of player url configurable (required, not possible in JWPlayer 6)
• MIT license