compute/hypervisor: ensure DBUS runs also on Debian

... and not only on Ubuntu.
It's a new dependency in OpenStack Juno (in Debian packaging).

Change-Id: I05fe1765674d77f46c8bb776a9833eaf1755a334

manifests/compute/hypervisor.pp

@@ -301,7 +301,7 @@ Host *
     })
   }
 
-  if $::operatingsystem == 'Ubuntu' {
+  if $::osfamily == 'Debian' {
     service { 'dbus':
       ensure => running,
       enable => true,

spec/classes/cloud_compute_hypervisor_spec.rb

@@ -255,10 +255,9 @@ describe 'cloud::compute::hypervisor' do
       end
     end
 
-    context 'with dbus on Ubuntu' do
+    context 'with dbus on Debian/Ubuntu' do
       let :facts do
         { :osfamily        => 'Debian',
-          :operatingsystem => 'Ubuntu',
           :vtx             => true,
         }
       end