Shopify/active_merchant — pull request #1410 by andrewpaliga (2014-10-02 20:50:33+00:00)
Title: add track_data support for Mercury

Add support for track data to [Mercury Payments](http://developer.mercurypay.com/docs/core-data-elements-xml-request/) gateway.

@jnormore @j-mutter can you please review?

cc @louiskearns