Made the Annotation builder automatically pass the EntityManager to Form Elements which need it.

Currently the only way I have found to get my 

`\DoctrineORMModule\Form\Element\EntitySelect`

elements to populate is, after creating the form using the `AnnotationBuilder`, calling

`$form->get('element_name')->setOptions(array('object_manager', $entityManager);`

I find this pretty messy so this little mod does it automatically.

Hope you like it.