fix logic in transport test server (#10)

The challenge acceptance logic was inverted since the challenge would
always fail as the server and client were using different cnonce values.
Make sure they are using the same cnonce, and invert the authorized
check.

transport_test.go

@@ -35,6 +35,7 @@ func TestTransport(t *testing.T) {
 			cred2, err := Digest(chal, Options{
 				Method:   r.Method,
 				URI:      r.URL.RequestURI(),
+				Cnonce:   cred.Cnonce,
 				Count:    cred.Nc,
 				Username: username,
 				Password: password,
@@ -43,7 +44,7 @@ func TestTransport(t *testing.T) {
 				http.Error(w, err.Error(), http.StatusBadRequest)
 				return
 			}
-			authorized = cred.Response != cred2.Response
+			authorized = cred.Response == cred2.Response
 		}
 		if !authorized {
 			w.Header().Add("WWW-Authenticate", chal.String())