Corrected HTTP user agent generation

The product token was plain and simply poorly generated.
The format ought to be <product token>/<version>, not
<product token>-<version>

See RFC 2068, section 3.8 (HTTP 1.1)
	http://tools.ietf.org/html/rfc2068#section-3.8
and RFC 1945, section 3.7 (HTTP 1.0)
	http://tools.ietf.org/html/rfc1945#section-3.7
Merge pull request #124 from meklu/master

Corrected HTTP user agent generation