Fix crash in runtime if PSK secret is missing

./Beremiz_service.py -s $PWD/psk2.txt -n beremiz /tmp/beremiz
Beremiz_service: 1.2-1378c18402c3+

Traceback (most recent call last):
File "./Beremiz_service.py", line 511, in <module>
ensurePSK(servicename, PSKpath)
File "/home/developer/WorkData/PLC/beremiz/beremiz/runtime/Stunnel.py", line 32, in ensurePSK
PSKgen(ID, PSKpath)
File "/home/developer/WorkData/PLC/beremiz/beremiz/runtime/Stunnel.py", line 23, in PSKgen
call(restart_stunnel_cmdline)
File "/home/developer/WorkData/PLC/beremiz/beremiz/runtime/spawn_subprocess.py", line 116, in call
pid = posix_spawn.posix_spawnp(cmd[0], cmd)
File "/home/developer/.local/lib/python2.7/site-packages/posix_spawn/_impl.py", line 120, in posix_spawnp
return _posix_spawn(lib.posix_spawnp, *args, **kwargs)
File "/home/developer/.local/lib/python2.7/site-packages/posix_spawn/_impl.py", line 111, in _posix_spawn
_check_error(res, path)
File "/home/developer/.local/lib/python2.7/site-packages/posix_spawn/_impl.py", line 10, in _check_error
raise OSError(errno, os.strerror(errno), path)
OSError: [Errno 2] No such file or directory: '/etc/init.d/S50stunnel'

#!/bin/sh

INKSCAPE=inkscape

for fname in `ls *.svg`; do
    for i in `cat $fname |grep -o -e '%%[^%]*%%'|sed 's/%//g'` 
    do
        if [ $i.png -nt $fname ]; then
 	    echo "Skip $i"
        else
	    rm  -f $i.png
	    echo "$INKSCAPE" $fname -z -e $i.png -i $i
	    "$INKSCAPE" $fname -z -e $i.png -i $i
        fi
    done
done

cp ico024.png brz.png
convert -compress none ico*.png brz.ico
rm -f ico*.png


convert -compress none poeico*.png poe.ico
rm -f poeico*.png