* Fix crash in IngressDetails

- Adds check in Ingress.getServiceNamePort() for a
  .spec.defaultBackend.resource instead of .spec.defaultBackend.service
Signed-off-by: Sebastian Malton <sebastian@malton.name>

* remove undefined
Signed-off-by: Sebastian Malton <sebastian@malton.name>

* Add comment about RequireExactlyOne
Signed-off-by: Sebastian Malton <sebastian@malton.name>