fix the bug that multiple activities start when clicking twice rapidly

import com.fsck.k9.Account;

import java.security.cert.X509Certificate;

import java.util.Locale;

import android.app.AlertDialog;

import android.app.DialogFragment;

import android.app.FragmentTransaction;

import android.content.DialogInterface;

import android.support.v7.app.AppCompatActivity;

import android.text.Editable;

import android.widget.Spinner;

import android.widget.TextView;

import com.fsck.k9.fragment.ConfirmationDialogFragment;

import com.fsck.k9.mail.ServerSettings.Type;

import com.fsck.k9.view.ClientCertificateSpinner;

        return -1;

    }

    private static long mLastClickTime = 0;

    private static boolean isActionValid() {

        long now = System.currentTimeMillis();

        boolean valid = (now - mLastClickTime > 1000);

        mLastClickTime = now;

        return valid;

    }

    public static void actionNewAccount(Context context) {

        if (isActionValid()) {

            Intent i = new Intent(context, AccountSetupActivity.class);

            context.startActivity(i);

        }

    }

    public void goToBasics() {

        stage = Stage.BASICS;