Automatic merge from submit-queue. If you want to cherry-pick this change to another branch, please follow the instructions <a href="https://github.com/kubernetes/community/blob/master/contributors/devel/cherry-picks.md">here</a>.

Bump Heapster to v1.6.0-beta.1

**What this PR does / why we need it**:
Bump Heapster to version v1.6.0-beta.1

**Release note**:
```release-note
Bump Heapster to v1.6.0-beta.1
```