#268: ObjectSelect does not set selected value for not lodaded entities

I had the same Problem that not loaded entities (for example associated entites) are not loaded in form selects. Therefore editing was a Problem - with this small code change proxy objects are loaded if they are not initialized. I know that this is solved in Doctrine 2.4 - it's a quick fix for People who had to work with Doctrine 2.3.4 :)