Unique sessions per Browser Window
At the moment, a session id is provided per Browser.
If a user opens two Browser windows with the same browser software,
both windows share one session id. This may lead to hickups/timing problems
of our socketbus system.
We need a session id allocation on a per-window-basis.
(from redmine: issue id 1880, created on 2014-10-06 by root, closed on 2014-10-07)