Use of django-filebrowser to allow static file uploads

In an effort to move away from file-sharing, or at least work around the Dropbox issues we've been having, this code change adds a 3rd-party "file browser" app for managing media files.  Admins can go to /admin/filebrowser/browse/ and navigate the media tree.  If they click "upload" and submit a file, it overwrites existing files on the server with the same name, or adds a new file.

The django-filebrowser app depends on another app called Grappelli, which as far as I can tell, only changes the styling of the admin interface.

Comments welcome on alternative approaches or different ways to expose/integrate the functionality with the existing admin interface.