Invalid session id should re-direct to login page
If the server looses the session id of a user, it should redirect from whatever page that happened from to the login page.
As an example, if the VM crashes and is restarted, it will start with a clean state and will have lost all session ids from the crashed run. If a user has either the overview window open, or one of the observatory data windows, the web browser will try to log in with the lost session id, and be refused access. In this case, the browser must be re-directed to the login page.