Remove '---' in default text of Instance Boot Source dropdown in Launch Instance dialog

[Omri Gazitt]

In bug https://bugs.launchpad.net/horizon/+bug/1302256 it was suggested that the style for default text for dropdowns should not contain leading and trailing '---'.

Therefore, the '--- Select source ---' text in Project -> Instances -> Launch instance -> Instance Boot Source should read 'Select source' instead.

[OpenStack Infra (hudson-openstack)]

Fix proposed to branch: master
Review: https://review.openstack.org/95362

[OpenStack Infra (hudson-openstack)]

Fix proposed to branch: master
Review: https://review.openstack.org/95589

[OpenStack Infra (hudson-openstack)]

Reviewed: https://review.openstack.org/95589
Committed: https://git.openstack.org/cgit/openstack/horizon/commit/?id=5da0ff5be02ea937790e7b12155db769804ff89b
Submitter: Jenkins
Branch: master

commit 5da0ff5be02ea937790e7b12155db769804ff89b
Author: Omri Gazitt <email address hidden>
Date: Sat May 24 02:03:00 2014 -0400

    Fix the default text for Instance Boot Source

    This change removes the leading and trailing '---' from the default
    text of the Instance Boot Source dropdown in the Launch Instance dialog.
    This change makes the default text more consistent with other dialogs.

    The localized files (django.po) were not modified because they will be generated
    from transifex eventually.

    Change-Id: I92bf8b8aa52724cbb851933132ee33bc87cd68b5
    Closes-Bug: #1322934