Kick out logout button for now
The logout button currently does nothing. While we could do the same as when closing windows, in the most recent meeting we decided to don't do that for now and instead keep the logout button as a visual indication for the upcoming feature #186.
So once we implement #186, we show the users that there is a separate logout button now. When clicking that logout button or the window exit button, it will then shortly explain that these are different features: the logout button kills the Briar process while the window exit button really only minimizes the window but keeps the process running.