Base all on xenial to save some space loading chunks, clean-up images

data/Dockerfiles/postfix/supervisord.conf

@@ -1,11 +1,11 @@
 [supervisord]
 nodaemon=true
 
-[program:rsyslog]
-command=/usr/sbin/rsyslogd -n
-autostart=true
-autorestart=true
+[program:syslog-ng]
+command=/usr/sbin/syslog-ng --foreground  --no-caps
 redirect_stderr=true
+autostart=true
+stdout_syslog=true
 
 [program:postfix]
 command=/opt/postfix.sh