[FIX] auto stop decision could not be undone

The worst nightmare for a user: select an "option" which could never be
changed again. This patch enables to reset the option to stop an empty
session on the host side.


Change-Id: I5a9c31c5b6df3eaa9c476f695f2e8dab108e745b
Reviewed-on: http://saros-build.imp.fu-berlin.de/gerrit/1111
Tested-by: Jenkins CI
Reviewed-by: Stefan Rossbach <srossbach@arcor.de>