Check if user is anonymous before calling PSYCHOMETRICS
LTI grade callbacks for example, come in with an anonymous user.  This causes a
stack trace in the psychometrics app that leads to the LTI service
getting a 404.  This adds a check before that callback gets registered.
Merge pull request #4295 from mitocw/cg/psycho_require_auth

Check if user is anonymous before calling PSYCHOMETRICS