Automatic merge from submit-queue (batch tested with PRs 51845, 51868, 51864)
Update sys spec to support docker 1.11-1.13 and overlay2.
Fixes https://github.com/kubernetes/kubernetes/issues/32536.
Update docker spec to:
1) Support overlay2;
2) Support docker version 1.11-1.13.
@dchen1107 @yguo0905 @luxas
/cc @kubernetes/sig-node-pr-reviews
```release-note
Kubernetes 1.8 supports docker version 1.11.x, 1.12.x and 1.13.x. And also supports overlay2.
```