Summary:
This links AppSumo sign-ups with Stripe subscriptions
and our billing pages. Different AppSumo tiers are supported by
different coupons on the standard plan. Configuration of this
is in stripe, and then cached in the database.
The front end is tweaked just enough to make completing a sign-up
possible. It is not yet friendly.
Not covered includes:
* Streamlining landing page.
* Making billing pages git clearer summaries of AppSumo states.
* Making flow through Cognito as graceful as possible - default
probably doesn't meet AppSumo requirements.
* Disabling site on cancellation/refund.
* Downgrades when more seats in use than lower tier allows.
Test Plan: api-level tests added. No front-end tests yet.
Reviewers: dsagal
Reviewed By: dsagal
Differential Revision: https://phab.getgrist.com/D2878