Add Consul support

Adding Consul to the mix. etcd is still there and still what we're using, but having consul installed already lets us more easily make the transition over time.

Note: Builds on the Vagrantfile branch, so review that first.
I chose ipaddress simply to avoid using 127.0.0.1. I don't want to use 127.0.0.1, since if we accidentally only bind to 127.0.0.1, the service won't be reachable from the outside.

I'm open to other suggestions.