refs https://github.com/TryGhost/Team/issues/1141
Showing canceled subscriptions provide a more complete picture of the activity of a member.
- Given there is no `member.product` object when a subscription is canceled, use the `member.subscriptions.price.product` objects instead of `member.products`.
- applied boy-scout rule for linter errors and and code formatting
- removed `multipleTiers` flag conditionals as it's now GA
- set up subscriptions as a separate mirage resource so they are easier to work with
- updated `PUT /members/:id/` endpoint to match real API's complimentary subscription behaviour
- modified mirage member serializer to match API output
Co-authored-by: Kevin Ansfield <kevin@lookingsideways.co.uk>
Co-authored-by: Peter Zimon <peter.zimon@gmail.com>
