Ensure Object is autoloaded.

When Object was renamed to CakeObject we broke behavior where plugins
and app code were relying on Object being configured in the autoloader
automatically.

Refs cakephp/debug_kit#450

lib/Cake/bootstrap.php

@@ -146,6 +146,7 @@
 App::uses('CakePlugin', 'Core');
 App::uses('Cache', 'Cache');
 App::uses('CakeObject', 'Core');
+App::uses('Object', 'Core');
 App::uses('Multibyte', 'I18n');
 
 App::$bootstrapping = true;