Add mailman templates in other languages

[Stefano Maffulli]

At the moment mailman only has templates for English.

On https://github.com/openstack-infra/config/tree/master/modules/mailman/files you can see that some of the html files have been modified to include the navigation elements from other openstack.org properties and the Google Analytics snippet.

By looking at the admin pages of the lists, other languages can be activated but only some parts of the pages are translated: see for example: http://lists.openstack.org/cgi-bin/mailman/listinfo/openstack-it and http://lists.openstack.org/cgi-bin/mailman/admin/openstack-it