Do a daemon reload for static units

Services that are deployed by systemd::timer need to trigger a
systemctl daemon-reload when the .service file is changed.

systemd::timer { 'foo.timer':
  timer_content   => $foo_timer,
  service_content => $foo_service,
  active          => true,
  enable          => true,
}

results in a foo.service that is neither active nor enabled. It is
a "static" unit that will be triggered by the foo.timer alone. This
fixes #190 and more specifically:

https://github.com/voxpupuli/puppet-systemd/issues/190#issuecomment-851701455

Signed-off-by: Simon Deziel <simon@sdeziel.info>