Prepare for React 16.

* feat(presence): display status in thumbnail and large video

- Create a React Component for displaying presence. It currently
  connects to the store for participant updates but in the future
  should not be as smart once more reactification occurs.
- Modify filmstrip css so the presence status displays horizontal
  center and below the avatar.
- Modify videolayout css so the presence status displays horizontal
  centered and with a rounded background.
- Dispatch presence updates so the participant state can be update.
- Update message position on large video update to ensure message
  positioning is correct.

* squash: do not show presence message if connection message is displayed