Improve the zone resources

[svc-paas-github]

we currently support the following zone related objects

zone_auth : DNS Authoritative Zone object.

In order to be able to have a complete implementation of DNS we need to also have

1 - zone_auth_discrepancy : Zone discrepancy information object.
2 - zone_delegated : DNS Delegated Zone object.
3 - zone_forward : DNS Forward Zone object.
4 - zone_rp : DNS Response Policy Zone object.
5 - zone_stub : DNS Stub Zone object.

I would say 2 and 3 should be maybe approached first.