changed ipv6? method to use regex to check for a valid IPv6 IP.

IPAddr class will use IPSocket.getaddress() to resolve potential hostnames
if a string is passed in to the constructor.  This will slowdown record
creation waiting for dns lookups to fail when creating new domains/records.
Removed ipaddr include
Added rspec tests for ipv4/6 and hostname validator
Merge pull request #20 from philipmuir/ipv6_method_check_change

Changed ipv6? method to use regex to check for a valid IPv6 IP.