Small changes for Braintree Blue

These changes allow for Client-Side Encryption tokens to be used as a credit card number, and a small change to AVS processing.

AVS information returned by Braintree is separate, with fields for postal code match and address match. Typically there is one value to represent both, and it's normally split out my AVSResult.

This pull request changes it to do exactly the opposite, and figure out a single code that signifies the result returned by Braintree.