LP1779158 Cache new queues / display active queues

LP1779158 Cache new queues / display active queues

* Only list active (non-complete) queues in the Vandelay queue selector
  combobox.
* Display an alert message when the user attempts to create a queue
  whose name collides with an existing queue for the user.
* Be sure newly created queues are added to the local cache of queues in
  the Vandelay service.
* Remove unused activeQueue list from vandelay.service to avoid having
  to maintain 2 separate queue caches.

Signed-off-by: Bill Erickson <berickxx@gmail.com>