Only query identifier_name variable from route.  Do not also allow same-named GET parameter

The identifier_name is configured as a route variable.  If the route variable exists it should be handled with fetch().  If no route variable exists it should be handled as findAll().  

This PR fixes the incorrect data handling of also allowing GET parameters to be named with identifier_name and take the place of the route variable.  fetch() would be called for a query to a route without a identifier_name but with a GET variable of the same name as identifier_name.