callback-arguments within ImmutableArrayType

If you use a callback as third "argument" of a field within `immutable_array`, it previously passes the callback itself to the callback, which doesn't make much sense. It passes now `$name`, `$type` and remaining values of the original array.

    $optionsCallback = function ($builder, $name, $type, $extra) {
        // $name == 'ttl';
        // $type == 'text';
        // $extra == array('foo', 'bar')
    }

    $form->add('options', 'sonata_type_immutable_array', array(
        'keys' => array(
            array('ttl',        'text', $optionsCallback, 'foo', 'bar')
        )
    ));