Shopify/active_merchant — pull request #658 by larspind (2013-04-11 07:54:22+00:00)
Title: Update quickpay notification parser to handle v6 of their API

Even though the helper is already setting protocol to v6, the notification parser could not parse notifications past v3.

In v4, the API was changed to do the POST as a form/multipart, but the notifications parser still tried to parse URLencoded POSTs.

Also, the checksum calculation was missing the two new v6 fields cardhash and cardexpire.