Yapstone gateway

 New gateway for Yapstone
www.yapstone.com
If it's required for following transactions, it needs to be packed into the `authorization`. Reference transactions (`capture`, `refund`, `void`, etc.) shouldn't have required options.

Can you give me more details on what form `property_code` takes? Is it a randomly assigned ID of some kind? Can/should it actually be passed in the `initialize` as one of the credentials?