Add interface designate to share the dns endpoint.
Update designate-k8s to implement provides side
of the interface and add endpoint data to the
relation app databag.
Update neutron-k8s to implement requires side of
the interface.
Add new options reverse-dns-lookup, ipv4-ptr-zone-prefix-size,
ipv6-ptr-zone-prefix-size.
Update neutron conf templates to add external dns
related configuration.
Change-Id: Ie7a481c7b90583981e7d68f6a54dfb0e6f1796dd
77067e7b4c