Add affiliate capability to rabbit checkout.

As a seller I want to be able to onboard new affiliates into rabbit checkout (with an approval process) so they can promote my product and get a commission. I as seller can configure the commission (either percentage of the final price or a fixed amount).

The affiliate should get a unique affiliate ID which he/she can attach to my checkout page URL. A cookie will be set so even if the potential customer is not buying immediately the affiliate gets the commission later (needs to be configurable as well).

In rabbit checkout I need a dashboard to see how much sells my affiliates made and an overview if a payout is due.