Support multiple cookies for follow_set_cookies

It appears that cookies.js expects the format ofthe `Set Cookies` header
to function. This sounds reasonable, but the original request cookies
are stored as a string not as key-value pair strings, so it needs to be
separated again to be forwarded correctly in the redirect.

lib/needle.js

@@ -542,7 +542,7 @@ Needle.prototype.send_request = function(count, method, uri, config, post_data,
         // if follow_set_cookies is true, insert cookies in the next request's headers.
         // we set both the original request cookies plus any response cookies we might have received.
         if (config.follow_set_cookies && utils.host_and_ports_match(headers.location, uri)) {
-          var request_cookies = cookies.read(config.headers['cookie']);
+          var request_cookies = cookies.read(config.headers['cookie'].split(';'));
           config.previous_resp_cookies = resp.cookies;
           if (Object.keys(request_cookies).length || Object.keys(resp.cookies || {}).length) {
             config.headers['cookie'] = cookies.write(extend(request_cookies, resp.cookies));