Renamed the codebase to RippingCluster

Since the new design is engine agnostic, removed HandBrake from the
class names.

webui/pages/errors/404.php

@@ -1,6 +1,6 @@
 <?php
 
-$main = HandBrakeCluster_Main::instance();
+$main = RippingCluster_Main::instance();
 $req  = $main->request();
 
 $this->smarty->assign('requested_page', htmlspecialchars($req->request_string()));

webui/pages/errors/unhandled-exception.php

@@ -1,6 +1,6 @@
 <?php
 
-$main   = HandBrakeCluster_Main::instance();
+$main   = RippingCluster_Main::instance();
 $config = $main->config();
 
 $this->smarty->assign('display_exceptions', $config->get('debug.display_exceptions'));