refs https://github.com/TryGhost/Team/issues/1252
We need a way to signal whether or not a Tier is active or archived, and
we'll be using the active flag in the same way we do for Offers.
refs https://github.com/TryGhost/Team/issues/1257
As well as fixing the code so that we do not create duplicate offer
redemptions going forward, we need to clean up the existing database.
We loop in code because the query to find and delete duplicates is complicated,
and will introduce more risk
refs https://github.com/TryGhost/Team/issues/1037
Free tier is now setup the same way as other tiers, to allow custom description/benefits. This change:
- adds a migration to add a default free tier for all sites
- adds a default fixture to insert a free tier for all new sites
refs https://github.com/TryGhost/Team/issues/1037
- adds new `type` column for tiers to differentiate between free and paid tiers
- all existing tiers are updated to be `paid` tiers
