[server] fix unittest_security for py3k - use source.binary_to_str instead of str(), helps when the backend returns memoryviews - fixup str vs bytes

#! /bin/sh -e

if [ -x "/etc/init.d/cubicweb-ctl" ]; then
    invoke-rc.d cubicweb-ctl restart || true
fi
 
 
#DEBHELPER#
 
exit 0