Code review comment for lp:~niedbalski/charms/trusty/rabbitmq-server/fix-lp-1489053

I think this change makes sense, especially in the general sense (not just in the OpenStack specific use case). For the openstack deployment case, dns resolution needs to be available for other services to properly work - however it has been argued (and I tend to agree) that simply deploying a rabbitmq-server cluster should "just work".

There's a minor lint issue that needs to be resolved, but other than that I'm happy to land this in the /next branches.