Support setting default theme for OpenStack Dashboard

[Nobuto Murata]

As a feature request, it would be nice if we could upload the collection of CSS and logo to customize dashboard UI.

http://docs.openstack.org/developer/horizon/topics/customizing.html
Such kind of customization is required for example to run private cloud with their corporate logo.

[Benjamin Kaehne (ben-kaehne)]

Furthering this;

If a whole custom theme is packaged and installed into "/usr/share/openstack-dashboard/openstack_dashboard/themes/", there is currently no way of being able to utilise this theme.

It seems there is only the ability to use or not use the ubuntu theme.

[Frode Nordahl (fnordahl)]

Fix proposed to branch: master
Review: https://review.openstack.org/#/c/387516/

[OpenStack Infra (hudson-openstack)]

Reviewed: https://review.openstack.org/387516
Committed: https://git.openstack.org/cgit/openstack/charm-openstack-dashboard/commit/?id=4834c461aa6e610182163767561b469d32a41f32
Submitter: Jenkins
Branch: master

commit 4834c461aa6e610182163767561b469d32a41f32
Author: Frode Nordahl <email address hidden>
Date: Mon Oct 17 15:46:12 2016 +0200

    Add support for setting default theme on OS L,M&N

    For Liberty we set CUSTOM_THEME_PATH.
    For Mitaka and Newton we set DEFAULT_THEME.

    Change-Id: I82cbd7622d43e93a6f1e456ad8fb95efa9963d69
    Related-Bug: 1626599

[OpenStack Infra (hudson-openstack)]

Fix proposed to branch: master
Review: https://review.openstack.org/400637

[OpenStack Infra (hudson-openstack)]

Reviewed: https://review.openstack.org/400637
Committed: https://git.openstack.org/cgit/openstack/charm-openstack-dashboard/commit/?id=5eec7b6648a99264c9312a99d2d45fb19bd55f52
Submitter: Jenkins
Branch: master

commit 5eec7b6648a99264c9312a99d2d45fb19bd55f52
Author: Frode Nordahl <email address hidden>
Date: Tue Nov 22 10:04:40 2016 +0100

    Extend AVAILABLE_THEMES when setting DEFAULT_THEME

    DEFAULT_THEME has no effect if the referenced theme is not listed
    in AVAILABLE_THEMES.

    Change-Id: I98f5a9bd789a584db786dbb7e34a48b26ff258fa
    Closes-Bug: 1626599