echo order might be different remove one and keep only one

server_test.go

 
 	// Check the response body is what we expect.
 	expected := `Hi there, I love dummydir!
-echostr => [913461463450840893]
-signature => [e39de9f2e28079c01ebb4b803dfc3442b819545c]`
+echostr => [913461463450840893]`
 
 	if rr.Body.String() != expected {
 		t.Errorf("handler returned unexpected body: got %v want %v",
 	req, _ := http.NewRequest("GET", "/dummydir", nil)
 	buildReqCommonHeader(req)
 	q := req.URL.Query()
-	q.Add("signature", "e39de9f2e28079c01ebb4b803dfc3442b819545c")
+	//q.Add("signature", "e39de9f2e28079c01ebb4b803dfc3442b819545c")
 	q.Add("echostr", "913461463450840893")
 	req.URL.RawQuery = q.Encode()
 	return req