When I refer a user to Querki, I should get a little goodie

(User Story, Investigate , Priority: High, Test Status: No automated tests yet , Reported By Justin du Coeur, )
Invites
Summary: Suggestion from Conor: it often proves effective for startups to give a sort of "referral bonus" to members who bring in other members.
This would need to be done with some care, because a naive implementation would be an invitation for abuse. But for example, reducing the referrer's membership fee based on the number of members they bring in who prove to be "real" totally makes sense.