public IHttpActionResult CreateCustomer(Customer customerToCreate)
        {
            db.Customers.Add ( customerToCreate );
            db.SaveChanges ( );

            responseText = "Customer Created";

            return Ok ( responseText );
        }
        public IHttpActionResult UpdateCustomer(Customer customerToUpdate )
        {
            try
            {
                db.Customers.Attach ( customerToUpdate );
                db.Entry ( customerToUpdate ).State = System.Data.Entity.EntityState.Modified;
                db.SaveChanges ( );
            }
            catch (Exception ex)
            {
                Console.WriteLine ( ex.Message );
            }

            responseText = "Customer Updated";

            return Ok ( responseText );
        }