Fixup openstack mailman template perms

We are using synchronize to copy the openstack mailman templates which
preserved the ownership and group and permissions of the source files on
bridge. This isn't a major problem but it is ugly so we fix it.

To fix it we set rsync_opts for synchronize to set a usermap and a
groupmap to map the bridge info to the data we want on the remote.

Change-Id: I209345cbe9e27beb18d1ba31e6715bf850bc022b

playbooks/roles/mailman-site/tasks/main.yaml

@@ -62,6 +62,9 @@
   synchronize:
     src: openstack/html-templates-en/
     dest: /srv/mailman/openstack/templates/en
+    rsync_opts:
+      - "--usermap=*:root"
+      - "--groupmap=*:list"
   when: mailman_site.name == "openstack"
 
 - name: Create site specific config