WIP
moved TransactionType to consts.py, created consts.PaymentPlanType
bugfix on core.BaseRequest.fetch(): the logic to test whether we had a valid response or not was wrong and the log call was never reached. we now also print out the response body
add --stop to nosetests, so that the testing process stops as soon as a test fails
WIP: masking credit card number before logging the request payload
Add util function to mask credit card from xml so we can log it
Merge pull request #13 from gabrielpugliese-luizalabs/ap-better-logging

Lots of changes as well as credit card masking before logging it.