add /inc/sandstone

usage of /inc/sandstone
<!--#set var="head-title" value="title in head" -->
<!--#set var="page-title" value="title on the page" -->
<!--#set var="page-desc" value="description on the page" -->
<!--#include virtual="/inc/sandstone/header.html" -->
... here are contents ...
<!--#include virtual="/inc/sandstone/footer.html" -->