Add label to order payment

[thenewguy]

It would be helpful to the customer if there was a way to display a short label with the order payment. For example, VISA ending in 1111 instead of just the identifier credit-card or whatever the payment method identifier is.

The payment_method is useful for the api but doesn't really give the customer enough information to remember which statement to check.

This seems generally useful and would probably be a good thing to include. If not, it would be helpful to allow adding additional fields here

[thenewguy]

As I've gotten deeper into this project the extra fields have become pretty powerful and necessary for site specific implementation. Maybe the simplest and most flexible solution is just to add the extra field to payments as well and then details like this could be added as needed.