This update for mailgraph fixes the following issues:

- Stop requesting an image from http://oss.oetiker.ch every time the mailgraph.cgi is opened
- add support (graphs) to postgrey and greylisting
- handle postscreen in the same way as smtpd
- added mailgraph.service file -> use systemd (boo#1116020)

  * add systemd support
  * add file mailgraph.service
  * set defaults in sysconfig file

- add support for rsyslog

This update was imported from the openSUSE:Leap:15.0:Update update project.