- added ``media_videos`` and ``media_images`` method to MediaLibrary model
- automatically creating library if none exists before creating items
- automatically selecting which vimeo image to select by size of image parent
- fixed admin
- Changed main url pattern to `^edit/$`
- added support for `success_url` GET/POST parameter to manipulate the success
url for views that have a `get_success_url` method. Just add a hidden field
to `mediaitem_delete.html` and `mediaitem_form.html`.
- fixed URL validation for Vimeo Pro URLs
- fixed MediaItem.delete method