initial sabre upgrade (needs lots of work - to wit: authentication, redo the browser interface, and rework event export/import)

vendor/sabre/http/lib/ClientException.php

@@ -0,0 +1,15 @@
+<?php
+
+namespace Sabre\HTTP;
+
+/**
+ * This exception may be emitted by the HTTP\Client class, in case there was a
+ * problem emitting the request.
+ *
+ * @copyright Copyright (C) fruux GmbH (https://fruux.com/)
+ * @author Evert Pot (http://evertpot.com/)
+ * @license http://sabre.io/license/ Modified BSD License
+ */
+class ClientException extends \Exception {
+
+}