add catchall backend class

classes/backend.php

@@ -0,0 +1,10 @@
+<?php
+class Backend extends Handler {
+
+	function loading() {
+		header("Content-type: text/html");
+		print __("Loading, please wait...") . " " .
+			"<img src='images/indicator_tiny.gif'>";
+	}
+}
+?>