Settings: Heads up meets N5X... N5X meets Google IO [4/4]
This patch adds the 4 possible user configurable settings.

1. Enable always expanded heads up notifications.
2. Set heads up snooze time
3. Set timout timer
4. Show updates of pending notifications

5. Add in app info screen a checkbox to enable heads up for the app.
   As another possibility aside the longpress on the notification on
   notification drawer.

Change-Id: Ia1b3559fcba435328a4d6a53fadc2ae055633d57