Fix editing permissions

Originally sparked by https://github.com/fle-internal/ka-lite-central/issues/169 on the central server repo, this fixes that issue -- so now on central, admins can access / edit data for the orgs they are a part of, and students can still safely edit their own accounts. 
I agree that this is confusing, yeah. Let's take a look, when you have a minute @dylanjbarth, at how we can simplify this view down to something easier to understand/verify.