Use custom event instead of Doctrine ones

This give us ability to use Entry ID to determine where to store images and it’s then more easy to remove them when we remove the entry.

src/Wallabag/CoreBundle/Event/EntrySavedEvent.php

@@ -0,0 +1,26 @@
+<?php
+
+namespace Wallabag\CoreBundle\Event;
+
+use Symfony\Component\EventDispatcher\Event;
+use Wallabag\CoreBundle\Entity\Entry;
+
+/**
+ * This event is fired as soon as an entry was saved.
+ */
+class EntrySavedEvent extends Event
+{
+    const NAME = 'entry.saved';
+
+    protected $entry;
+
+    public function __construct(Entry $entry)
+    {
+        $this->entry = $entry;
+    }
+
+    public function getEntry()
+    {
+        return $this->entry;
+    }
+}