private static HttpResponseMessage PushData(List<ActivityData> data)
        {
            string json = JsonConvert.SerializeObject(data);
            HttpResponseMessage resp = PostRequest(json, dataUrl);

            return resp;
            /*HttpResponseMessage resp = null;
            foreach (ActivityData datum in data)
            {
                string json = JsonConvert.SerializeObject(datum);
                resp = PostRequest(json, dataUrl);
            }
            return resp;*/

        }