Address dynamic class property deprecation warnings

templates/Alert.php

@@ -8,6 +8,10 @@
 
 class Alert extends SubTemplate
 {
+	private $_type;
+	private $_message;
+	private $_title;
+
 	public function __construct($title = '', $message = '', $type = 'alert')
 	{
 		$this->_title = $title;