Update for Lita 3.0, use Ruby whois library

This plugin looked like it could use a little freshening up, so I've
gone ahead and bumped it to use Lita 3.0, have all the right metadata,
use a pure-ruby library for WHOIS lookups, and added in test coverage.
Merge pull request #1 from esigler/refresh-and-use-a-library

Update for Lita 3.0, use Ruby whois library