title: Android onCreate() not called with Notification
body: <p>I have met with interesting intent workflow handling.
  I create a notification like this:</p>
  
  <pre><code>    NotificationCompat.Builder mBuilder = new NotificationCompat.Builder(context)
          .setSmallIcon(R.drawable.abc_textfield_search_default_holo_dark).setContentTitle("Мероприятие изменилось")
          .setContentText(eventToShow.valueAt(i).name + " " + eventToShow.valueAt(i).date).setAutoCancel(true);
      Intent resultIntent = new Intent(context, MainActivity.class);
      resultIntent.putExtra(MainActivity.NOTIFICATION_EVENT_DISPLAY, eventToShow.valueAt(i).id);
      PendingIntent resultPendingIntent = PendingIntent.getActivity(context,0,resultIntent,PendingIntent.FLAG_UPDATE_CURRENT);
      mBuilder.setContentIntent(resultPendingIntent);
      NotificationManager mNotifyMgr = (NotificationManager) context.getSystemService(Context.NOTIFICATION_SERVICE);
      mNotifyMgr.notify(eventToShow.valueAt(i).id, mBuilder.build());
  </code></pre>
  
  <p>When notificataion is arrived to user, i expect that when he clicks on it MainActivity.class will handle this intent.
  I process information about intent inside <code>MainActivity.onCreate()</code>.</p>
  
  <p>Everything goes ok if i click on notification outside my app. Activity correctly processing this intent and shows what i expected.</p>
  
  <p>But when i click on notification inside my app there is no new instanse of my <code>MainActivity.class</code> And <code>onCreate()</code> is not firing. I thought that it will be created new Instance of <code>MainActivity.class</code></p>
  
  <p>Can you explain me is this a default behavior and how should i handle this situation?</p>
  
  <p>After testing my app i find next.</p>
  
  <p>a) MainActivity -> get notification -> Close app -> Open app(MainActivity) -> press notification -> Notification opening new instance of MainActivity as expected.</p>
  
  <p>b) MainActivity -> get notification -> press notification -> nothing is happened</p>