Don't write a URL for host 0.0.0.0 in jnp-service.url

If a user binds naming to 0.0.0.0, the NamingServiceURLWriter writes jnp://0.0.0.0:1099 in the data/jnp-service.url file. That's a useless URL for a management client, the intended consumer of the info in this file. See JOPR-254 for further details.