此目录结构为:
{皮肤目录名}/controller/{控制器名}/ {皮肤目录名}/views/layout/ {皮肤目录名}/views/{视图目录名}/
皮肤名:night,默认首页SiteController使用的视图名:site, 其目录结构为:
night/controller/SiteController.php night/views/layout/main.php night/views/site/index.php