Use contact_id as reference in civicrm_stripe_customers and don't require an email address for payment

Minor changes to improve formatting and set a generic domain name

See merge request extensions/stripe!2

Jamie McClelland authored 6 years ago and mattwire committed 6 years ago

When you select a priceset with the value 0, the form properly hides
the credit card input fields.

However, we still try to submit a credit card to stripe which results in
an error.