Add rekease.update event

This is what I meant with #2034 although it is not complete yet. I now use the frontend movie.update.id event which completely reloads the movie. We should also have a release.update.id event that only updates the release. My JS however is not up to par. To bring this a bit further, I think the release plugin should have its own JS files in its own static folder. That would help expanding the Media ;)