Authorize.Net: Add maestro as supported card type

Maestro is supported as a card type by some merchant accounts that
Authorize.Net backs up to. Unfortunately the Authorize.Net sandbox does
not support Maestro, so a remote test was not possible.

Closes #1304.
Worldpay: Improve address defaults

Previously, we defaulted parts of the address that were unspecified.
Now we also default the parts that are explicitly set to a blank value.

Closes #1311.
Braintree Blue: Pass name when tokenizing

Closes #1306.
Moneris: Add :avs_enabled option
Wirecard: Improve error handling

If Wirecard is having a really bad day it is possible for their API to
return error responses that are not contained within the W_JOB element.

This adds a new method to correctly parse these Wirecard
having-a-bad-day responses, and also pluck out the ErrorCode as well.

Closes #1315.
Merge pull request #1317 from Shopify/moneris_avs_flag

Add :avs_enabled option for Moneris