public ActionResult ChangePassword(StudentChangePasswordVM model)
        {
            if (!ModelState.IsValid)
            {
                return View();
            }

            if (model.NewPassword != model.NewPasswordRepeat)
            {
                ModelState.AddModelError("Error", "New password dont match");
                return View(model);
            }

            UserRepository<Student> stuRepo = new UserRepository<Student>();
            Student student = stuRepo.GetByID(model.StudentID);
            Passphrase hash = PasswordHasher.Hash(model.OldPassword);

            if (PasswordHasher.Equals(model.OldPassword, student.Salt, student.Hash))
            {
                Passphrase hash2 = PasswordHasher.Hash(model.NewPassword);

                student.Salt = hash2.Salt;
                student.Hash = hash2.Hash;

                stuRepo.Save(student);
            }
            else
            {
                ModelState.AddModelError("Error", "Old password dont match");
                return View(model);
            }

            return RedirectToAction("Index", "Student");
        }
        public ActionResult ChangePassword()
        {
            StudentChangePasswordVM model = new StudentChangePasswordVM();
            UserRepository<Student> stuRepo = new UserRepository<Student>();

            Student student = stuRepo.GetByID(Models.AuthenticationManager.LoggedUser.ID);

            model.StudentID = student.ID;

            return View(model);
        }