Add auto_initialize tru in BaseListener del file type to support Symfony 2.3

As explaned in Symfony 2.3 upgrade file :


 * The *_SET_DATA events are now guaranteed to be fired *after* the children
   were added by the FormBuilder (unless setData() is called manually). Before,
   the *_SET_DATA events were sometimes thrown before adding child forms,
   which made it impossible to remove child forms dynamically.

   A consequence of this change is that you need to set the "auto_initialize"
   option to `false` for `FormInterface` instances that you pass to
   `FormInterface::add()`:

   Before:

   ```
   $form = $factory->create('form');
   $form->add($factory->createNamed('field', 'text'));
   ```

   This code will now throw an exception with the following message:

   Automatic initialization is only supported on root forms. You should set the
   "auto_initialize" option to false on the field "field".

   Consequently, you need to set the "auto_initialize" option:

   After (Alternative 1):

   ```
   $form = $factory->create('form');
   $form->add($factory->createNamed('field', 'text', array(
       'auto_initialize' => false,
   )));
   ```