Add list-zone capability to pdns_control
Removed unused \n at end of line.
Add delete-zone to pdns_control

The implementation needed an update to the DNSBackend base class,
with a new method called deleteDomain(zone, id); We pass both because a backend might use ID (like GSQL) or the actual name.
We did this so we could reuse the delete-zone-query which was perfectly fine except it deletes based on ID.
Add list-all-zones to pdnssec.
Purge cache when deleting a domain.
Correct usage of Ueberbackend
Add delete-zone to pdnssec.
Remove deleteDomain from uberbackend and call directly.
Added metadata delete and correct handling of response