public UsersViewModel()
{
Title = "View Users";
Users = new ObservableCollection <User> ();
LoadUsersCommand = new Command(async() => ExecuteLoadUsersCommand());
MessagingCenter.Subscribe <AddUserPage, User>(this, "AddUser", (Action <AddUserPage, User>)(async(obj, user) =>
{
var newUser = user as User;
Users.Add((User)newUser);
await UserDataStore.AddUserAsync((User)newUser);
}));
}
