shutdown-functions not used via docker stop

[bebehei]

docker stop does not send signals to supervisor-processes correctly. The signals get lost somewhere on the way between docker -> /opt/run -> supervisord -> /opt/supervisor/*

At least:

• There is no log-entry in the corresponding-log file which should indicate the intention to stop the service via init.d-script.
• docker needs exactly 10s to stop the container all the time:

$> docker stop --help
[...]
   -t, --time int   Seconds to wait for stop before killing it (default 10)
$> time docker stop mon-dev
mon-dev
docker stop mon-dev  0.01s user 0.00s system 0% cpu 10.346 total
$>