Add Brazil VAT (know as CNPJ) validator

[andrebazoli]

My company is launching in Brazil next month and I wouldn't like to have to add another library to only validate the VAT in Brazil.

Do you mind if I open a PR to add this validation?

It will require some small changes to getCountry logic because Brazil VAT doesn't start with the country code and also add the / to removeExtraChars method.