Fixes includes
Refactor subject helper
Fixes gemspec dependencies
Add validations and minitest-validations
Add presence validations for DadosPortador
Add presence validations for DadosPedido
Add presence validations for FormaPagamento
Add presence validations for Cieloz::Base
Switches from minitest-activemodel to minitest-matchers + shoulda
Refactors FormaPagamento, and includes debito a vista validation tests
Validates FormaPagamento/credito
Validates parcelamento
Validates if a operation is called against an instantiated FormaPagamento
Validates DadosPortador numero and validade
Validates indicador / codigo seguranca
Validates DadosPortador / codigo seguranca
Validates DadosPortador / nome portador