Bug#778499: purging does not remove all configuration files

[Trek]

Package: systemd
Version: 215-11

purging the systemd package leaves the system dirty, as it does not
remove /etc/sytemd/system/*remote-fs* (or something similar) and
possibly other files and directories created on postinst

one cannot simply remove the /etc/systemd directory as it may contains
files from other packages like syslog.service from rsyslog created on
postinst by init-system-helpers

adding to prerm the systemctl disble remote-fs.target commad may be
sufficient to remove the symlinks on /etc, but I do not know how
systemd works

ciao