Stregsystem giftcards

[falkecarlsen]

Some fembers have requested the ability to buy a giftcard for stregsystemet, enabling fembers to gift other fembers a payment.

This would likely require one more level of mobilepayment differentiation, such that we have ordinary payments, already-processed payments, and now also giftcard payments.

I could imagine having a new model Giftcards, which have a sender-member, receiver-member, amount, and possibly a mobilepay transaction ID. Processing a giftcard should then mark it as "used" and update the members amount by using the make_payment function.