public PkgDownloader(string url)
        {
            var client = new GregClient(new Greg.AuthProviders.BasicProvider("test", "test"), url);

            var req      = HeaderCollectionDownload.ByEngine("dynamo");
            var response = client.ExecuteAndDeserializeWithContent <List <PackageHeader> >(req);

            Console.WriteLine("file downloaded from " + url + req.Path);

            Lists = response.content;
        }