ha: Make neutron-ha-tool start after haproxy and neutron-server

Otherwise, neutron-ha-tool fails to start.

Of course, we only do that when neutron-server and neutron-l3 roles are
on the same cluster, and both with HA.
Merge pull request #96 from vuntz/order-constraints

ha: Make neutron-ha-tool start after haproxy and neutron-server
Handle multiple DNS forwarders correctly

Oslo.config expects list optionts to be separated by
comma, not space (see
http://docs.openstack.org/developer/oslo.config/types.html)

(cherry picked from commit ef4b976faaf3a95797356ae2e8527d0c94f9a4fe)
Merge pull request #111 from dirkmueller/release/roxy/master

Handle multiple DNS forwarders correctly