TW-22: Code formatting
TW-22: Notifies the team when status changes

* when a user logs in (with the form or the cookie)
* when a user disconnect
TW-22: Flags the tile "OFFLINE" when user is offline
TW-22: Fixes tests
Merge pull request #11 from teamwall/feature/TW-22_React_to_status_changes

Feature/tw 22 react to status changes