Allow changing of ResolvedFormTypeFactory

Added a new service for the ResolvedTypeFactory. The service name is based on the symfony service name.

src/Silex/Provider/FormServiceProvider.php

@@ -19,6 +19,7 @@ use Symfony\Component\Form\Extension\Csrf\CsrfProvider\SessionCsrfProvider;
 use Symfony\Component\Form\Extension\HttpFoundation\HttpFoundationExtension;
 use Symfony\Component\Form\Extension\Validator\ValidatorExtension as FormValidatorExtension;
 use Symfony\Component\Form\Forms;
+use Symfony\Component\Form\ResolvedFormTypeFactory;
 
 /**
  * Symfony Form component Provider.
@@ -77,9 +78,14 @@ class FormServiceProvider implements ServiceProviderInterface
                 ->addExtensions($app['form.extensions'])
                 ->addTypeExtensions($app['form.type.extensions'])
                 ->addTypeGuessers($app['form.type.guessers'])
+                ->setResolvedTypeFactory($app['form.resolved_type_factory'])
                 ->getFormFactory()
             ;
         });
+        
+        $app['form.resolved_type_factory'] = $app->share(function ($app) {
+            return new ResolvedFormTypeFactory();
+        });
 
         $app['form.csrf_provider'] = $app->share(function ($app) {
             if (isset($app['session'])) {