Introduce new meta keys

Author: Marco Pereirinha

cloudinary-image-management-and-manipulation-in-the-cloud-cdn/php/class-sync.php

@@ -49,6 +49,8 @@ class Sync implements Setup, Assets {
 		'sync_error'     => '_sync_error',
 		'cloudinary'     => '_cloudinary_v2',
 		'folder_sync'    => '_folder_sync',
+		'syncing'        => '_cloudinary_syncing',
+		'downloading'    => '_cloudinary_downloading',
 	);
 
 	/**