Consistent handling of choiceField in trove

[Andrew Bramley]

There appears to be a sort of standard way to populate choiceField such that:

If the choice field list has items then the initial value will be 'Select <object type>'

and if the choice field list is empty then the value will be 'No <object type>s available'

In the Trove Launch dialog we don't do this for the Restore From Backup choiceFIeld - instead it just contains an initial '-'

Change the trove launch dialog restore from backup choice list to follow the preferred pattern using 'Select backup' and 'No backups available'

[OpenStack Infra (hudson-openstack)]

Fix proposed to branch: master
Review: https://review.openstack.org/106452

[OpenStack Infra (hudson-openstack)]

Reviewed: https://review.openstack.org/106452
Committed: https://git.openstack.org/cgit/openstack/horizon/commit/?id=047e5af10823c00e52d641d3ab1f597f26aa932b
Submitter: Jenkins
Branch: master

commit 047e5af10823c00e52d641d3ab1f597f26aa932b
Author: Andrew Bramley <email address hidden>
Date: Fri Jul 11 13:41:32 2014 -0400

    Consistent handling of choiceField for backups

    CHanged the way we initially populate the restore
    backups choice field in the trove launch dialog
    so that it is consistent with other choice fields
    in horizon dashboard e.g. compute->instances

    An empty choiceField now says
    'No backups available'
    and a populated choiceFIeld will have an initial
    selection of
    'Select backup'

    Change-Id: I1b0f57656bd649ad92268789f35c9ba77223dbc9
    Closes-bug: #1340867