[bugfix] Doctrine needs to process parameters otherwise they will enter the query improperly

The bugfix made by ChubV (https://github.com/KnpLabs/knp-components/pull/51) introduced a problem where certain parameters were no longer processed properly, causing them to enter the final query as their classname instead of being translated into an ID.

I have made a small change so that each parameter is first processed by Doctrine to make sure the proper value is selected for the query.