change amex code from 18 to 180
lib/baby-braspag/payment_method.rb
Merge pull request #4 from Baby-com-br/lh-dp-change-amex-code

Change Amex Code from 18 to 180
Merge branch 'master' of github.com:Baby-com-br/braspag into ruby-2
Merge branch 'ruby-2' of github.com:Baby-com-br/braspag into ruby-2