[Designate] IPv6 detection check added

The current code assumes that the nameserver value configured
in tempest.conf is one of these two options only: IPV4 or IPV4:PORT
There is no handling for IPV6 addresses(with/without PORT).
(If IPV6 is set it causes traceback).

This patch adds support for IPV6.

Change-Id: I6ee56fcc1f00bc55012bcd1895bddce5acfa07d4
1 file changed