Feature/638

[zsinnema]

Closes #638

Implemented solution: use #637 for setting JH user quotas

How to test this PR: assign some user quotas, start Jupyterhub pod and check the assigned quotas

kubectl -n <namespace> get pvc  # check the user pvc size
kubectl -n <namespace> describe pod <pod name>  # check the cpu/mem request and limit

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