ViewModel for the Invitation class
        public static InvitationViewModel Create(IRepository repository, Invitation invitation = null)
        {
            Check.Require(repository != null, "Repository must be supplied");

            var viewModel = new InvitationViewModel {
                Invitation = invitation ?? new Invitation()
            };

            return(viewModel);
        }
        public static InvitationViewModel Create(IRepository repository, Invitation invitation = null)
        {
            Check.Require(repository != null, "Repository must be supplied");

            var viewModel = new InvitationViewModel {Invitation = invitation ?? new Invitation()};

            return viewModel;
        }