public async Task<ActionResult> GetSignInUrl(string id)
        {
            string filename = String.Format("{0}.docx", id);

            DownloadViewModel viewModel = new DownloadViewModel(
                blobId: filename
            );

            string blobUrl = await viewModel.GetSecureUrl();

            return Redirect(blobUrl);
        }
        public async Task<ActionResult> DownloadSignIn(string id)
        {
            string filename = String.Format("{0}.docx", id);

            DownloadViewModel viewModel = new DownloadViewModel(
                blobId: filename
            );

            DownloadPayload blobData = await viewModel.GetStream();

            return File(blobData.Stream, blobData.ContentType, filename);
        }