public async Task<IHttpActionResult> PutProduct(Guid id, Product product)
        {
            if (!ModelState.IsValid)
            {
                return BadRequest(ModelState);
            }

            if (id != product.Id)
            {
                return BadRequest();
            }

            product.DateModified = DateTime.Now;

            db.Entry(product).State = EntityState.Modified;

            try
            {
                await db.SaveChangesAsync();
            }
            catch (DbUpdateConcurrencyException)
            {
                if (!ProductExists(id))
                {
                    return NotFound();
                }
                else
                {
                    throw;
                }
            }

            return StatusCode(HttpStatusCode.NoContent);
        }
        public async Task<IHttpActionResult> PostProduct(Product product)
        {
            if (!ModelState.IsValid)
            {
                return BadRequest(ModelState);
            }

            product.DateCreated = DateTime.Now;
            product.DateModified = DateTime.Now;

            db.Products.Add(product);
            await db.SaveChangesAsync();

            return CreatedAtRoute("DefaultApi", new { id = product.Id }, 
                new ProductViewModel()
                {
                    Id = product.Id.ToString(),
                    Title = product.Title,
                    Price = product.Price
                });
        }