Fix libvirt_uuid file generation

When libvirt_uuid file is created, it requires /etc/libvirt directory which is
added by libvirt package. So the package should be required

Change-Id: Id290fff5c6c7c78916b9f878ad04928b2ea46c82

manifests/migration/libvirt.pp

@@ -71,7 +71,8 @@ class nova::migration::libvirt(
     if ! $::libvirt_uuid {
       $host_uuid = generate('/bin/cat', '/proc/sys/kernel/random/uuid')
       file { '/etc/libvirt/libvirt_uuid':
-        content => $host_uuid
+        content => $host_uuid,
+        require => Package['libvirt'],
       }
     } else {
       $host_uuid = $::libvirt_uuid

spec/classes/nova_migration_libvirt_spec.rb

@@ -53,6 +53,10 @@ describe 'nova::migration::libvirt' do
         }
       end
 
+      it { is_expected.to contain_file('/etc/libvirt/libvirt_uuid').with({
+        :content => '0000-111-111',
+      }).that_requires('Package[libvirt]') }
+
       it { is_expected.to contain_augeas('libvirt-conf-uuid').with({
         :context => '/files/etc/libvirt/libvirtd.conf',
         :changes => [ "set host_uuid 0000-111-111" ],