public async Task<ActionResult> SaveAssignmentCategory(AssignmentCategoryViewModel model)
        {
            //ModelState.AddModelError("EmailSubject", "Test Error.");

            if (ModelState.IsValid)
            {
                var category = new AssignmentCategory()
                {
                    Id = model.Id,
                    OwnerLevel = model.OwnerLevel,
                    OwnerId = model.OwnerId,
                    Title = model.Title
                };

                if (string.IsNullOrEmpty(model.Id))
                    await _assignmentManager.InsertCategoryAsync(category);
                else
                    await _assignmentManager.UpdateCategoryAsync(category);

                return Ok(category);
            }
            return BadRequest(ModelState);
        }