Fix errors with the media edit form

* remove reference to old players, which was causing problems with the keyframe picker
* fix the function to get the duration of the video (for the iTunes duration field)
* add a local copy of TinyMCE so that we do not have to keep the 3.0 templates around
* Fix a problem where the TinyMCE would not always get applied to the description field
* Make the edit form full width, rather than half width.  Looks nicer this way.

These changes have been tested in the latest versions of Firefox and Chrome, as well as ie9.