HEAD doesn't return Content-Type and Content-Length

[dobesv]

The headers sent back by the HEAD HTTP method should be identical to those for a GET, including the Content-Type and Content-Length.

Just a minor compliance issue, though, I don't think HEAD is used much by HTTP clients out there.

See http://www.w3.org/Protocols/rfc2616/rfc2616-sec9.html

[dobesv]

Put in a fix for this in https://github.com/cloudhead/node-static/pull/34