Add whois2.publicinternetregistry.net.rb

From the new file,

      # ICANN registrars use whois2.publicinterestregistry.net,
      # a whitelisted, non-rate-limited server.

We currently set our own server to use this, à la

      case domain.tld
        when 'org' then Whois::Server.factory(:tld, '.org', PIR_WHOIS_SERVER_HOST,
            { adapter: Whois::Server::Adapters::Afilias })
        else Whois::Server.guess(domain.name)
       end

(Better way?)

This works fine except `Parser.parser_klass` can't find it, so I've added this file.

Wasn't apparent to me how I could add real value with tests but open to ideas.

There's a couple of misc fixes I spotted too.