auth
auth/context.go
Test our getClientAuth helper, switch to table-based tests. Our getClientAuth helper was being tested implicitly when we tested our verifyClient helper, but let's test them separately. While we're at it, let's use table based tests instead of copy and paste. I noticed a lot of copy/paste errors while I was updating this, and the less test code we have and the easier we make it to test new edge cases, the better of we are.