BUGFIX: Return a RootForm for AssetAdmin so Form get the correct Fields on POST

Solves issues with GridField and uploading on the root folder (/assets/)

code/controllers/AssetAdmin.php

@@ -85,6 +85,15 @@ JS
 		CMSBatchActionHandler::register('delete', 'AssetAdmin_DeleteBatchAction', 'Folder');
 	}
 		
+	/**
+	 * Return the root 'asset' folder CMSFields
+	 * 
+	 * @return FieldList
+	 */
+	public function RootForm() {
+		return $this->getEditForm(singleton('Folder'));
+	}
+	
 	/**
 	 * Show the content of the upload iframe.  The form is specified by a template.
 	 */