Add `order_id` to Charges and `my_customer_id` to Customers created in sample app. (#35)
Add `order_id` to Charges and `my_customer_id` to Customers created in sample app. (#35)

This shows off using the `metadata` field to include application-specific information
in the Stripe objects.

These metadata fields can be used for looking up the associated Order/Customer in your
app's backend, given the Order/Customer from Stripe.
stripe/example-ios-backend