(SIMP-4929) Add network service deps to rsyslog.service (simp#67)

Add a systemd rsyslog.service override file that fixes a service
ordering problem present with older versions of rsyslog.  The
override ensures the network.target and network-online.target units
are added to the 'Wants' and 'After' lists for the rsyslog.service.

NOTE:  This module now uses camptocamp-systemd, which, per its
metadata.json, **requires** puppet >= 4.10.10.  As such, puppet
4.7, 4.8, and 4.9 testing has been removed from GitLab and
TravisCI configuration.

SIMP-4929 #close

.fixtures.yml

@@ -26,6 +26,8 @@ fixtures:
       repo: https://github.com/simp/puppetlabs-stdlib
     stunnel:
       repo: https://github.com/simp/pupmod-simp-stunnel
+    systemd:
+      repo: https://github.com/simp/puppet-systemd
     tcpwrappers:
       repo: https://github.com/simp/pupmod-simp-tcpwrappers
   symlinks: