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/layout/admin/default/javascript/jquery.js

@@ -1 +1 @@
-jquery-1.8.2.min.js
+jquery-1.11.1.js

www/layout/admin/default/javascript/prototype.js

@@ -1 +1 @@
-prototype-1.7.1.0.js
+scriptaculous/prototype.js

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));