redirect to homepage when websocket is closed due to session timeout

this is a simplest reaction of gui for now, the proper handling is still to be decided upon (see e.g. #163; this also doesn't cover the case if the timeout is experienced during the http request (e.g. saving draft).
fix to a bug in a prev commit (bdc0634)
Merge remote-tracking branch 'origin/1.0-bugfix' into 1.0-bugfix