Fix django_openstack_auth translation setup

The locale files and directory setup in django_openstack_auth is
different from all other projects, we need to handle the translations
extra.

The patch adds two new slave scripts for the usual translation jobs that
share setup via the common library.

Two new jobs are created which are hooked into JJB and Zuul.

Also, the filtering of commits has been moved from all files
to the common function filter_commits. The grep in this function has
been simplified.

Change-Id: Id76b88b2583f3cdddecd41adce5f18363ee19e53
Merge "Fix django_openstack_auth translation setup"