instead of just applying the cookie to the hostname you accessed jfa-go
on, it is applied to the one you set in jfa-go. The result is you'll
have to login twice if you access on localhost:8056 instead
of accounts.jellyf.in.
user-auth.go contains slightly adjusted versions of auth.go functions,
for authorizing jellyfin users (admin or not). Refactored auth.go so that
most code is shared. User auth isn't hooked up yet, nor has it been
tested.