Pass options to SitePageForm

Not passing options prevented the add_to_navigation checkbox from
ever being added to the form.

application/src/Service/Form/SitePageFormFactory.php

@@ -9,7 +9,7 @@ class SitePageFormFactory implements FactoryInterface
 {
     public function __invoke(ContainerInterface $services, $requestedName, array $options = null)
     {
-        $form = new SitePageForm;
+        $form = new SitePageForm(null, $options);
         $form->setCurrentTheme($services->get('Omeka\Site\ThemeManager')->getCurrentTheme());
         return $form;
     }