Automatic merge from submit-queue (batch tested with PRs 47896, 50678, 50620, 50631, 51005)

allow heapster option defaults to be set - kubectl top node|pod

**Release note**:
```release-note
NONE
```

Allows downstream / outside consumers of `NewCmdTopNode` and `NewCmdTopPod` commands to set project or case-specific heapster option defaults.

Related downstream PR: https://github.com/openshift/origin/pull/15764

cc @fabianofranz