Allow Logging to stdout with separate Error Log Channel (#718)

* Add dedicated error logging writer

* Document new errors to stdout flag

* Update changelog

* Thread-safe the log buffer

* Address feedback

* Remove duplication by adding log level

* Clean up error formatting

* Apply suggestions from code review

Co-authored-by: Joel Speed <Joel.speed@hotmail.co.uk>

pkg/middleware/jwt_session.go

@@ -57,7 +57,7 @@ func (j *jwtSessionLoader) loadSession(next http.Handler) http.Handler {
 
 		session, err := j.getJwtSession(req)
 		if err != nil {
-			logger.Printf("Error retrieving session from token in Authorization header: %v", err)
+			logger.Errorf("Error retrieving session from token in Authorization header: %v", err)
 		}
 
 		// Add the session to the scope if it was found