private void Login(object sender, EventArgs e)
        {
            var tweetController = new TweetController();
            var cookie          = tweetController.Login(tvLogin.Text, tvPassword.Text);

            if (cookie != null)
            {
                var intent = new Intent(this, typeof(LogoutActivity));
                intent.PutExtra("Cookie", cookie);
                StartActivity(intent);
            }
            else
            {
                Toast.MakeText(this, "Login failed. Try again!!!", ToastLength.Short).Show();
            }
        }