Debug log when token found in revocation list

The auth_token middleware didn't log when a token is rejected
because it's in the revocation list. This adds a log message so
that it's easier to debug problems.

Change-Id: I1388ed04641d209ba2083a1096488edc22267ebe
Enhance tests for auth_token middleware

There was code in _verify_uuid_token that was not covered by unit
tests. This change increases the coverage.

Change-Id: I63e171a0a8e63ae599c967adc9ff09670063b807
Related-Bug: #1174499
Merge "Debug log when token found in revocation list"