Added logging message for API authentication failure

app/Api/Auth.php

@@ -31,6 +31,7 @@ class Auth extends Base
         } elseif ($this->isAppAuthenticated($username, $password)) {
             $this->checkProcedurePermission(false, $method);
         } else {
+            $this->logger->error('API authentication failure for '.$username);
             throw new AuthenticationFailure('Wrong credentials');
         }
     }