Refactored Cnab240::Arquivo::Arquivo specs
Added debugger gem as a development dependency
The following methods now expect an instance of IO (e.g. an instance of File):
  Cnab240::Arquivo::Arquivo#save_to_file
  Cnab240::Arquivo::Arquivo.load_from_file
  Cnab240::Builder#load_from_file
  Cnab240::PagamentoBb#save_to_file
  Cnab240::PagamentoBradesco#save_to_file
  Cnab240::PagamentoItau#save_to_file
  Cnab240::PagamentoSicoob#save_to_file

The gem version was raised to 0.0.20
Removed unnecessary specs fixtures directory
Updated README.md
Fixed specs on Ruby 1.9.3
Fixed specs on Ruby 1.9.3
The following methods were reverted to expect a string containing the file name:
  Cnab240::Arquivo::Arquivo#save_to_file
  Cnab240::Arquivo::Arquivo.load_from_file

The new method was added to allow reading contents from an I/O interface:
  Cnab240::Arquivo::Arquivo.load
Cnab240::Builder#load_from_file renamed to Cnab240::Builder#load
Moved implementation common to all helper classes to a Cnab240::Helper class
Merge pull request #7 from erichmachado/master

Possibilidade de trabalhar com qualquer instância de IO através da API (File, Tempfile, StringIO, etc...)