Remove default serialization of all view vars.

This is an unsafe default and a comment warning is not enough.

src/Controller/AppController.php

@@ -51,22 +51,4 @@ public function initialize()
  //$this->loadComponent('Security');
  //$this->loadComponent('Csrf');
  }
-
- /**
- * Before render callback.
- *
- * @param \Cake\Event\Event $event The beforeRender event.
- * @return \Cake\Http\Response|null|void
- */
- public function beforeRender(Event $event)
- {
- // Note: These defaults are just to get started quickly with development
- // and should not be used in production.
- // You should instead set "_serialize" in each action as required.
- if (!array_key_exists('_serialize', $this->viewVars) &&
- in_array($this->response->getType(), ['application/json', 'application/xml'])
- ) {
- $this->set('_serialize', true);
- }
- }
 }