add systemd support

@pperonna this will be integrated in puppet, services will be easier to handle with systemctl.

journalctl will also work and display a 1 month rolling buffer (default for systemd), it should bring some handy commands such as :

journalctl -u daqmanager --since='1 day ago'

systemctl restart daqmanager

I'm wondering if we should add this in crontab to receive mails on warning (setting MAILTO to ntof-experts maybe), not sure yet will talk about this with @rcevenin :

  0  0  *  *  * root journalctl --priority=warning --quiet -u daqmanager --since='1 day ago'

data/CMakeLists.txt

+
+# Do not use GNUInstallDirs there (would use lib64 instead of lib)
+install(FILES daqmanager.service
+  DESTINATION "lib/systemd/system"
+  COMPONENT Runtime)