Dummy gateway is no longer used if no gateway is specified
Adding checkGateway method
Adding gateway() method
Adding card property
Using card property for card data
Removing duplicate method
Adding setCard method
Using OmniPay credit card object
Adding authorize method
Adding gatewayRequest method which contains common logic for gateway methods
Adding capture method
Adding completePurchase method
Adding refund method
Adding void method
Returning $this from setCard to allow chaining