Add a common label to all resources on `kube apply'

Ok, so basically I will do:

```
switch t := obj.(type) {
case *api.Pod:
  if err := mergeMaps(t.Labels, src); err != nil {  }
case *api.Service:
  if err := mergeMaps(t.Labels, src); err != nil {  }
case *api.ReplicationController:
  if err := mergeMaps(t.Labels, src); err != nil {  }
  if err := mergeMaps(t.DesiredState.PodTemplate.Labels, src); err != nil {  }
default:
  // Unknown generic objects
  // ..use Reflection to find t.Labels
}
```

Do I understand correctly?