Support hardware-aware affinity for pods on k8s cluster

In case of deploying a Container Network Function on the VNF of a Kubernetes
cluster with the blueprint "CNF Support with ETSI NFV specifications" [1], the
Pods may be scheduled on the same physical Compute server while they are
labeled with anti-affinity rules [2]. The anti-affinity Rule can deploy the
Pods on different worker nodes, but the worker nodes may be in the same
server.

In this spec, we propose a hardware-aware affinity for Pods. This is achieved
by labeling the worker nodes with the identifier of deployed Compute servers.
In Tacker, MgmtDriver can handle the installation of Kubernetes cluster as a
VNF instance, and the `instantiate_end` script can help the process to make
and assign the labels.

[1] https://blueprints.launchpad.net/tacker/+spec/cnf-support-with-etsi-nfv-specs
[2] https://kubernetes.io/docs/concepts/scheduling-eviction/assign-pod-node/