Give persistent hostnames to long-lived instances

[dpoirier]

Using route 53 or something - e.g. role.environment.project.cakt.us - so we can refer to hostnames in our configuration and if we have to replace an instance it doesn't break the configuration of all the other servers.

Also this would help rabbitmq even across reboots of the same instance to keep the same hostname; it doesn't like hostname changes.