Hi!
Thanks for this library, it’s a really nice mix of flexible and batteries-included. I’m finding myself struggling a little with a multi-tenancy situation that isn’t using PG schemas - I wonder if you wouldn’t mind giving your thoughts?
Essentially User belongs to Account, but User.email is only unique within the Account. Accounts are segmented by the accessing domain, and there’s some plug middleware in place that pulls the correct Account into the conn.private storage, but I can’t work out a way of ensuring that this gets merged into the User Context for queries etc within Pow without re-implementing the entire context class from scratch. This is an option, but it’s a bit of a rubbish one 
prefix in repo_opts gets special cased, but would you be interested in a PR that maybe pulled a Ecto queryable or the like from the conn which could be merged in to scope User accesses?
If there’s a system for this already then apologies for having missed it, would love to know what you think!
