public IHttpActionResult PutContact(int id, Contact contact)
        {
            if (!ModelState.IsValid)
            {
                return BadRequest(ModelState);
            }

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

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

            try
            {
                db.SaveChanges();
            }
            catch (DbUpdateConcurrencyException)
            {
                if (!ContactExists(id))
                {
                    return NotFound();
                }
                throw;
            }

            return StatusCode(HttpStatusCode.NoContent);
        }
        public IHttpActionResult PostContact(Contact contact)
        {
            if (!ModelState.IsValid)
            {
                return BadRequest(ModelState);
            }

            db.Contacts.Add(contact);
            db.SaveChanges();

            return Ok(contact);
        }