Missing array init in Admin Backend, jquery & prototype update

If no page list data for admin backend is read, the pages array is not
set, init it, so it doesn't throw an error.

Update jquery 1 to 1.11.1, jquery 2 to 2.1.1 and prototype to 1.7.1.0

www/libs/Class.Admin.Backend.inc

@@ -162,6 +162,8 @@
 
 			// get the session pages array
 			$pages = $_SESSION["PAGES"];
+			if (!is_array($pages))
+				$pages = array ();
 
 //$this->debug('pages', $this->print_ar($pages));