Summary: Ref T2787. `Product` is currently a fairly heavy object, but as Phortune develops it makes a lot of sense to make it a lighter object and put more product logic in applications. Convert it into a fairly lightweight reference to applications. The idea is that Phortune is mostly providing a cart flow, and applications manage the details of products.
Test Plan: Funded an initiative for $1.
Reviewers: btrahan
Reviewed By: btrahan
Subscribers: epriestley
Maniphest Tasks: T2787
Differential Revision: https://secure.phabricator.com/D10634
