support dependencies for kustomize yamls

[balopat]

As @mxey pointed out on Slack:

"Skaffold does not support dependencies through Kustomize yet. I only saw this TODO comment https://github.com/GoogleContainerTools/skaffold/blob/master/pkg/skaffold/deploy/kustomize.go#L92, but there is no issue to track this. Would it make sense to add a command to Kustomize or maybe use Kustomize as a library to list the dependencies, rather than Skaffold interpreting the kustomization itself?"

[r2d4]

We can do this now

kubernetes-sigs/kustomize#265
kubernetes-sigs/kustomize#144

[dgageot]

Let's close this one because we do support dependencies now