Minor changes to make it work with .PT and .BR domains

* Add test for getting the name server for Portugal TLD (.pt)
* Add test for getting the name server for Brazil TLD (.br)
* Bug fix: Make sure we have a secondary whois server before connecting
  * This was preventing .PT domains to be queried
* Add full support for character encoding
  * This is needed so we can correctly read .PT and .BR whois which are ISO-8859-1 encoded
* Add visitor for PT domains
  * Very simple version just like the UK one, only parsing the domain creation date
* Add visitor for BR domains
  * Very simple version just like the UK one, only parsing the domain creation date