New payment method: Stripe. Subscription support only. StripeSubscriptionPaymentMethod implements the integration. It calls the Omnipay gateway implemented for stripe subscriptions at Omnipay\Stripe\Subscription which handles the actual logic to create subscriptions at Stripe.
Projects marked as permanent campaign that have enabled Stripe as payment method can now allow to receive donations via Stripe subscriptions.
Rewards flagged as subscribable items to allow Project owners to specify monthly amounts.
This PR adds the following behaviour:
StripeSubscriptionPaymentMethodimplements the integration. It calls the Omnipay gateway implemented for stripe subscriptions atOmnipay\Stripe\Subscriptionwhich handles the actual logic to create subscriptions at Stripe.