* Initial "join room" feature.
* React correctly to remotely joined rooms.
* Leaving rooms implemented both locally using the room menu
   in nheko, and reacting properly when leaving a room remotely 
   from another client.

closes #11

- Rooms without any history will be shown.
- Room's state will be kept in sync and any updates will be visible.

- Add border width on Badge

Logout from the current session and invalidate the current token