Save MRR to subscriptions (#386)
Save MRR to subscriptions (#386)

refs https://github.com/TryGhost/Team/issues/1456

- Sets the `mrr` column correctly when updating a subscription
- We can use this value in the future to have an improved calculation of mrr_delta, but we first need to have the migration in place
- Updated missing cancelled -> canceled
TryGhost/Ghost,TryGhost/Ghost,TryGhost/Ghost