Add boilerplate scaffolding for Phortune subscriptions
Summary:
Ref T6881. This roughs in the major objects, support classes, and controllers.
- Show subscriptions on account detail.
- Browse all account subscriptions.
- Link to active subsciptions from merchant detail.
Test Plan: Clicked around in the UI. There's no way to create subscriptions yet, so I basically just kicked the tires on this. I probably missed a few things that I'll clean up in followups.
Reviewers: btrahan
Reviewed By: btrahan
Subscribers: epriestley
Maniphest Tasks: T6881
Differential Revision: https://secure.phabricator.com/D11482