Add support for SKPaymentTransactionObserver method and Promotions

[PasqualePuzio]

Hi,

I've recently tried to promote my in-app purchases by using the new features available on iOS 11.

However I haven't managed to do that because my app doesn't support the SKPaymentTransactionObserver method https://developer.apple.com/documentation/storekit/skpaymenttransactionobserver/2877502-paymentqueue

Here there are more information about promotions https://developer.apple.com/app-store/promoting-in-app-purchases/

Do you think you can add this feature?

Thanks