Allow any member of a repo to delete subscription

https://trello.com/c/SrdebCDE/345-ensure-that-only-repo-payer-can-disable-it

There is an issue where a repo subscription cannot be deleted by anyone other than the user who created it. We think this shouldn't be the case; users who have access to the repo should be able to disable Hound when there is a subscription.
Useless assignment to variable - `subscription`.