IPv6 support

[eligrey]

Does this fork of ipcat support ipv6? If not, you should look at @dsamarin's pull request that added IPv6 support to the Go implementation of ipcat to see what changes might be necessary.

[frewsxcv]

i think we might be fine since ruby's IPAddr supports IPv6:

[7] pry(main)> IPAddr.new('fe80:cd00::211e:729c').to_i
=> 338292682821229838246455806028416971420

ipcat-ruby/lib/ipcat.rb

Line 19 in fd9a5f8

Integer === ip ? ip : IPAddr.new(ip).to_i

once the upstream ipcat merges that pull request, i can pull the datacenter data down to this repo and confirm