public IHttpActionResult GetAuthor(int id)
        {
            Author author = context.Authors.Find(id);
            if (author == null)
            {
                return NotFound();
            }

            var authorViewModel = new AuthorViewModel(author);

            return Ok(authorViewModel);
        }
        public IHttpActionResult PostAuthor(AddAuthorBindingModel authorBindingModel)
        {
            if (!ModelState.IsValid)
            {
                return BadRequest(ModelState);
            }

            var author = new Author(authorBindingModel.FirstName, authorBindingModel.LastName);

            context.Authors.Add(author);
            context.SaveChanges();

            var authorViewModel = new AuthorViewModel(author);

            return CreatedAtRoute("DefaultApi", new { id = authorViewModel.Id }, authorViewModel);
        }