Add HttpFoundationExtension to FormServiceProvider.

This closes all of the issues with `$form->bind($request)` does not
work issues.

src/Silex/Provider/FormServiceProvider.php

@@ -13,13 +13,14 @@ namespace Silex\Provider;
 
 use Silex\Application;
 use Silex\ServiceProviderInterface;
+use Symfony\Component\Form\Extension\Core\CoreExtension;
+use Symfony\Component\Form\Extension\Csrf\CsrfExtension;
 use Symfony\Component\Form\Extension\Csrf\CsrfProvider\DefaultCsrfProvider;
 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\FormFactory;
 use Symfony\Component\Form\FormRegistry;
-use Symfony\Component\Form\Extension\Core\CoreExtension;
-use Symfony\Component\Form\Extension\Validator\ValidatorExtension as FormValidatorExtension;
-use Symfony\Component\Form\Extension\Csrf\CsrfExtension;
 use Symfony\Component\Form\ResolvedFormTypeFactory;
 
 /**
@@ -52,6 +53,7 @@ class FormServiceProvider implements ServiceProviderInterface
             $extensions = array(
                 new CoreExtension(),
                 new CsrfExtension($app['form.csrf_provider']),
+                new HttpFoundationExtension(),
             );
 
             if (isset($app['validator'])) {