Sync with latest Drupal Gardens code

There is code in Drupal Gardens that did not yet find its way into the Media Gallery module on drupal.org. This patch should help sync them up. It contains several changes that don't seem to have issues elsewhere (mostly addition of JS and CSS, as well as additional "remove" functionality for items in the gallery).

Note that the patch creates new "css" and "js" directories.

In addition, the two hover bubble images attached to this issue also need to be added into the "images" directory in CVS.