Windowed video re-positioned to center of viewport

Playback size is also responsive to viewport size. There are still some odd situations where the user _could_ resize the viewport to crop the video, but those are edge cases and most users would not want a window sized that way anyway.

IE11 z-index bug also fixed - see this post: http://mediabrowser3.com/community/index.php?/topic/4922-server-web-client-ie11-mis-layering/

Pull it and check it out, or if you can wait I'll get an azure server setup for a sandbox so you can see it in action.