asset versionning

app/config/config.yml

@@ -27,7 +27,8 @@ framework:
         save_path: '%kernel.project_dir%/var/sessions/%kernel.environment%'
     fragments: ~
     http_method_override: true
-    assets: ~
+    assets: 
+        json_manifest_path: '%kernel.project_dir%/web/build/manifest.json'
     php_errors:
         log: true