protected async void GetJson(JsonLoadedListener listener, string url)
        {
            var http     = new HttpClient();
            var response = await http.GetAsync(url);

            if (response.IsSuccessStatusCode)
            {
                var content = await response.Content.ReadAsStringAsync();

                listener(Codeplex.Data.DynamicJson.Parse(content));
                return;
            }

            listener(null);
        }
        protected async void GetJson(JsonLoadedListener listener, string url)
        {
            var http = new HttpClient();
            var response = await http.GetAsync(url);

            if (response.IsSuccessStatusCode)
            {
                var content = await response.Content.ReadAsStringAsync();

                listener(Codeplex.Data.DynamicJson.Parse(content));
                return;
            }

            listener(null);
        }