public ActionResult AddAssignment(Assignment newAssignment)
        {
            if (ModelState.IsValid)
            {
                var database = new CourseRepository();
                database.AddAssignmentToCourse(newAssignment);
                return(RedirectToAction("Gradebook", new { id = newAssignment.CourseId }));
            }

            return(View("AddAssignment", newAssignment));
        }