We had client-side notification stacking in the tray since launch, but now we want to stack notifications in the notifications page, in API responses and in email bundles.
There has been a bit of drift between actual schemas in production and
what's implied by the migrations.
And fixed some tests that were relying on everyone always watching.
ref: https://fizzy.37signals.com/5986089/cards/2322
The access involvement changes exposed that this test wasn't doing what it said it was. For this to be a self-assignment the event creator and assignee need to be the same