Default credit card per user

When an order is completed, we save the credit card used as the user's
default credit card. When creating a new order, we use an existing
credit card (if it exists) and attach it to the order before reaching
the payment state.
Revert unrelated hash format changes
Wrong hash key here
Add extra default logic sanity check
WIP Expedited exchanges

When a return authorization is saved
Given a return item has a requested exchange
Then an exchange shipment for the exchange items for the return authorization are generated immediately

Given an exchange shipment has been generated pre-return
Given a customer has not returned their item after X days
Then create a new order with the exchange shipment and capture payment for the full amount of the items