Nova

WIP .. all nova controller code works on single node (single OC) for now.
this dependency is redundant. Looking at the source I see:

from nova:
````
Nova_config<| |> ~> Exec['post-nova_config']
````

from nova::api
````
exec { 'nova-db-sync':
      command     => '/usr/bin/nova-manage db sync',
      refreshonly => true,
      subscribe   => Exec['post-nova_config'],
    }
````