Add ajax account update.  Make modal init async.

* Fix signup errors from server.

* Add "update" method to $auth service.

* Add account settings modal.

* Update modal scope initialization logic so that it can be
  asynchronous.

* Add "timeInput" directive for form inputs that are backed by a Time
  instance.

* Add signup modal html.

* Change serialization format of wake/sleep to number of minutes for
  easy conversion to Time objects.

* Add route/action for getting user account info.

* Modify registrations#update for ajax.