Use Pimple instead of Core\Registry and add Monolog for logging

app/Model/Notification.php

@@ -117,7 +117,7 @@ class Notification extends Base
 
         foreach ($events as $event_name => $template_name) {
 
-            $listener = new NotificationListener($this->registry);
+            $listener = new NotificationListener($this->container);
             $listener->setTemplate($template_name);
 
             $this->event->attach($event_name, $listener);
@@ -135,8 +135,7 @@ class Notification extends Base
     public function sendEmails($template, array $users, array $data)
     {
         try {
-            $transport = $this->registry->shared('mailer');
-            $mailer = Swift_Mailer::newInstance($transport);
+            $mailer = Swift_Mailer::newInstance($this->container['mailer']);
 
             $message = Swift_Message::newInstance()
                             ->setSubject($this->getMailSubject($template, $data))
@@ -149,7 +148,7 @@ class Notification extends Base
             }
         }
         catch (Swift_TransportException $e) {
-            debug($e->getMessage());
+            $this->container['logger']->addError($e->getMessage());
         }
     }