- Places supervisor/daemon/worker under the new Cron class

- Updates endpoints
- Integrates queue worker with MailPoet mailer
- Fixes script activation check logic

lib/Models/SendingQueue.php

@@ -0,0 +1,12 @@
+<?php
+namespace MailPoet\Models;
+
+if(!defined('ABSPATH')) exit;
+
+class SendingQueue extends Model {
+  public static $_table = MP_SENDING_QUEUE_TABLE;
+
+  function __construct() {
+    parent::__construct();
+  }
+}