whois.dns.lu to support registrar and contacts info

Changes were made on the following files:
* `lib/whois/record/parser/whois.dns.lu.rb`
* `spec/fixtures/responses/whois.dns.lu/status_registered.expected`

The file `spec/whois/record/parser/responses/whois.dns.lu/status_registered_spec.rb` was generated by command `rake spec:generate`