Add "Global Payments" Integration

With Realex, all moneys received through card payments are available for us to draw down, then any subscription and transactional fees are billed monthly. This makes the allocation of payments in our Opera accounts system MUCH easier compared to the other providers (SagePay & Stripe) who deduct their fees 1st and only make the balance of the transaction available to draw down.

This method of handling card payments is causing us a lot of extra work with allocating payments received to order progressed, and this is not maintainable as we plan to grow our online presence.