Add support for cookie based authentication in the initial handshake

[ctradu]

Add a new function open/4, which is open/3 with a forth parameter, which becomes an additional header - Cookie. Assume this authentication cookie was obtained in a previous step using a http auth mechanism.

My usage scenario is using ibrowse to do the http authentication step in the following manner:

Answer = ibrowse:send_req(Url, Headers, post, Body, Options),
case Answer of
        {ok, Status, ResponseHeaders, _ResponseBody} ->
            Cookies = get_cookies(ResponseHeaders),
            AuthCookie = find_cookie(AuthCookiePattern, Cookies),
            {ok, AuthCookie}
       %...
end
HandshakeRequest = wsock_handshake:open(Resource, Url, Port, AuthCookie)

[madtrick]

@ctradu in any case I'll take a look to the cookie thing (even if it's to late for you)