Shopify/active_merchant — pull request #382 by DanKnox (2012-06-21 01:33:53+00:00)
Title: Add Metrics Global gateway

A client of mine switched their payment processor from Authorize.net to [Metrics Global](http://metricsglobal.com/). It turns out that Metrics Global built their API to exactly mimic the Authorize.net API to make it easy for their customers to transition. I cloned the `AuthorizeNetGateway` class and updated the documentation to match the Metrics Global information. I also updated the tests to account for the few places where their responses do differ and added their public demo account information to the fixtures file.

I did not port over the recurring billing functionality since my client does not use it and I am unable to test it thoroughly at this time.

Let me know if you need me to change anything.