Comment 7 for bug 1715066

Reviewed: https://review.openstack.org/534355
Committed: https://git.openstack.org/cgit/openstack/horizon/commit/?id=2ab0ea8c6a6eb8f1d6d6e04959426487c558c4a9
Submitter: Zuul
Branch: stable/pike

commit 2ab0ea8c6a6eb8f1d6d6e04959426487c558c4a9
Author: Ivan Kolodyazhny <email address hidden>
Date: Tue Sep 26 17:26:45 2017 +0300

    Add render method to ThemableCheckboxSelectMultiple

    Django 1.11+ doesn't have RenderMixin class for widgets, so we have to
    implement render method for ThemableCheckboxSelectMultiple to get it
    rendered in a correct way with all supported Django versions until we
    find a better solution for our widgets implementation.

    Change-Id: I656afb162e130f2b77853368945b74330bedf747
    Closes-Bug: #1715066
    (cherry picked from commit c13d6da80e7a68c28aa0adfe63459be8a6dbedfd)