CreditCard class should support card tokens.

[akDeveloper]

CreditCard class should manage a token reference of itself.
Some gateways supports the feature of exchanging the sensitive data of a credit card with a token reference.

Merchants can use this token to fulfill payments.
In this case purchase or authorize methods should accept a CreditCard object or a string reference of CreditCard.

Instead of changing the signature of these methods, it is better add support of token in CreditCard class.

So inside these methods should check if $creditcard->token is available to complete the action with token instead of card data.

[akDeveloper]

CreditCard class should ideal be replaced with this package in next major release.