Allow CreditCard to be used autonomously from Payment. 

Interface on PaymentMethod.create_profile was changed to create_payment_profile. This was to change from taking a Payment to taking a CreditCard (or other source) so that payment profiles can be created without a Payment.

Added user, bill_address, and payment_method to CreditCard and copy this data on successful Payments prior to creating a payment profile.

Migration includes copying data for all credit cards with a payment profile.

Please review and comment. Thanks!