Rename $LATTICE_COORDINATOR_IP to $CONSUL_SERVER_IP

I think technically the `$LATTICE_COORDINATOR_IP` variable is really to allow diego cells' consul client to connect with the consul server; which might (currently is) running on the coordinator VM/job. Perhaps consider renaming it to `CONSUL_SERVER_IP` in preparation for allowing reuse of an existing consul server cluster and/or deployment of consul server outside of the coordinator job VM.