This review request combines and modifies both http://reviews.reviewboard.org/r/1594 and http://reviews.reviewboard.org/r/1590/ .  These requests have since been discarded.

I've created an Extensions resource for the Djblets API.  Authorized users can get the entire list of extensions from a GET on /api/extensions/, or info on a particular extension through a GET on /api/extensions/[extension id]/.  Enabling and disabling extensions is accomplished through a PUT on /api/extensions/[extension id]/ with an "enabled" boolean parameter.

The UI has been updated to use this API through AJAX queries.  Errors during enabling/disabling should be displayed in a modal dialog box (see screenshot).

Some of the CSS, and a few of the images have been copied from the RB project.  Not sure if we want that duplication.  Just a heads up.

Another note - I've added a new field to the RegisteredExtensions table.  This means, if you're following along with me, you'll need to perform an evolve on your DB.

All feedback welcome.

All manual at this point.  Which is unfortunate.  :(