Allow translators to translate the dashboard.
This commit sets up related files according to the infra guide [1]. Also
removes Babel related entries in setup.cfg. They are not sufficient as
Django requires two PO files (django and djangojs).
[1] https://docs.openstack.org/infra/manual/creators.html#django-projects
Change-Id: Ifc616d58a794d94f2f36823dcfee4f0165981b12
Task: 22816
Story: 2002867