Add possibility to delete A/AAAA record

[asmaps]

Add a possibility to reset a record.

E.g. if you create a domain while you have IPv6 and the host that will update the domain does not the IPv6 you had while creating the host will stay in the record forever.

[apnof]

Hi, had the same problem;

workaround:

• convert your IPv4 to IPv6,
• take IPv6 and update from any IPv6 enabled connection

Example:

• get IPv6 via this site: https://www.ultratools.com/tools/ipv4toipv6Result?address=99.88.77.66
  (0:0:0:0:0:ffff:6358:4d42 in this case)
• update: http://<your fqdn>:<your secret>@ipv6.www.hopper.pw/nic/update?myip=0:0:0:0:0:ffff:6358:4d42