* change controller.Notebooks.load_note_revisions() to select and return User_revision objects
* change controller.Notebooks.save_note() to use User_revision objects for new_revision and previous_revision as well
* update client to deal with new load_note_revisions() return values (make sure all uses of revisions_list are updated)
* update client to deal with new new_revision/previous_revision
* update changes pulldown to show username along with each timestamp
* update model.Invite to load redeemed_username along with redeemed_user_id
* display the redeemed username next to each email address in the "share this notebook" note
Dan Helfman