Improved scheduled publishing interface.

-  There is an easy way to publish immediately (most common)
-  Added datepickers
-  Popups are now iframes that are isolated from surrounding page
Improved VersionCommit.__unicode__ representation.
Add a widgy.admin.js to keep the fancybox code

Also adds a loading spinner while the iframe is loading.
Merge branch 'improved_committing'

* improved_committing:
  Add a widgy.admin.js to keep the fancybox code
  Improved VersionCommit.__unicode__ representation.
  Improved scheduled publishing interface.