Github pages, HTTP headers

The answer is no, however we can stimulate html header on html pages using <meta http-equiv> tag.

<meta http-equiv="last-modified" content="Sun, 10 Feb 2013 14:00:46 GMT " />
<meta http-equiv="cache-control" content="Private" />
<meta http-equiv="Expires" content="600" />

You can embed these snippets into the HTML page.

I asked this to Github admins, and they told me that "it is not possible" to change headers. They added this issue to wishlist.