Serve container streaming in localhost.

[Random-Liu]

After kubernetes/kubernetes#64006, kubelet will proxy container streaming between apiserver and container runtime.

Making container streaming serve on localhost will make the connection more secure. We should support this and add a knob to switch between the localhost streaming server and old streaming server.

For Kubernetes <= 1.10, users can use old streaming server; for Kubernetes 1.11, users can use local streaming server to make it more secure.

For this version, old streaming server should still be the default to avoid backward compatibility issues, but:

1. We should disable the TLS (disabled by default today anyway), or else the old streaming server won't work with Kubernetes 1.11;
2. In the release note, we should tell user that they can switch to localhost streaming server if they are using Kubernetes 1.11+.