Manage the messagebus service on non-RHEL RHEL-like platforms

Previously, the test for enabling the "messagebus" service checked
for "$operatingsystem == RedHat", which only matches on RHEL;
$operatingsystem is "CentOS" on CentOS machines. I think we want
"$osfamily" here, which is "RedHat" on CentOS machines.

I also added a test for "$operatingsystem != Fedora" to preserve
the existing behavior on those machines, which as far as I can
tell do not require this service.

Change-Id: I020591006df87a9766cefbe36740940915924180

manifests/compute/libvirt.pp

@@ -16,7 +16,7 @@ class nova::compute::libvirt (
     }
   }
 
-  if($::operatingsystem == 'RedHat') {
+  if($::osfamily == 'RedHat' and $::operatingsystem != 'Fedora') {
     service { 'messagebus':
       ensure   => running,
       enable   => true,