adding string limits for billing address

@odorcicd @bslobodin 
https://pagseguro.uol.com.br/v2/guia-de-integracao/api-de-pagamentos.html

This adds a list of limits for the strings send to PagSeguro. If present, I just slice it. If the string is too big, PagSeguro explodes. ¬¬
Such a strange thing, it's optional, but only ``BRA`` is allowed. Can we exclude it altogether?