Address k8s del_svc api change

[simon-mo]

Fix Kubernetes Container Manager:

CHANGELOG (Kubernetes)
delete_namespaced_service() now takes an required body (delete option) parameter. 
Refactor service storage to remove registry wrapper kubernetes/kubernetes#59510

Spec:
https://github.com/kubernetes-client/python/blob/master/kubernetes/docs/CoreV1Api.md#delete_namespaced_service

Error like

  File "/Users/simonmo/Desktop/clipper/clipper/clipper_admin/clipper_admin/kubernetes/kubernetes_container_manager.py", line 393, in stop_all
    namespace='default', name=service_name)
TypeError: delete_namespaced_service() takes exactly 4 arguments (3 given)

will now go away.

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[dcrankshaw]

LGTM

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