title: RecurringApplicationCharge charging
body: <p>Using oauth we are getting the shop's token with the purpose of using it for creating bills using shopify_api. We successfully create ApplicationCharge and RecurringApplicatiomCharge. The user can confirm or deny that request. But we have a question regarding the RecurringApplicationCharge: will the shopify notify our backend at each withdrawal of money for subscription from the account ? Or should we check the withdrawal fact using API in order to know to prolong the subscription or not?</p>