1091427: pulp-server should run systemctl daemon-reload on upgrade/removal

Some systemd macros were missing from the pulp-server spec to automatically run
systemctl daemon-reload. Adding to %postun covers both upgrades and removals.

NOTE: this could be done in %post, but doing it in %postun seems to be the
convention. A macro exists for %postun but not for %post.
Merge pull request #935 from beav/1091427

1091427: pulp-server should run systemctl daemon-reload on upgrade/removal