convert localhost to 127.0.0.1

A specific ip address is a bit more tolerant of certain VM port forwarding implementations.

In my case, the `start-cluster.sh` script would hang here:

    until curl -s "http://localhost:${CONTAINER_PORT}/ping" | grep "OK" > /dev/null 2>&1;
    do
        sleep 3
    done

because curl -s would never return anything.