Removing a DNS address record removes the resource entry

[Alberto Donato]

There seems to be a UI issue where removing a DNS address entry removes the whole resource, even if it has more than one IP associated.
To reproduce:

- create a DNS record like "test" A "1.2.3.4"
- create a DNS record like "test" AAAA "2001::1"
- select one of those and select "remove record"

Both entries are gone.

This seems to be because the UI calls "domain.delete_dnsresource", which removes the whole resource (ignoring the passed IP address).
It should likely call "domain.delete_address_record" instead.