Add bup package to backup_server.pp

The backup_server.pp only included template data, add the bup
package requirement.

Change-Id: Ic0ec963aba386ea07712c47ffb5faccfc1223085

modules/openstack_project/manifests/backup_server.pp

@@ -4,4 +4,7 @@ class openstack_project::backup_server {
   class { 'openstack_project::template':
     iptables_public_tcp_ports => [],
   }
+  package { 'bup':
+    ensure => present,
+  }
 }