Bump cluster autoscaler to 0.5.1

Cluster-autoscaler: bump version to 0.5.0

Merge pull request kubernetes-retired#1990 from kubernetes/foxish-fea…

…ture-freeze-1

Feature freeze 1.5 PR

Merge pull request kubernetes-retired#1721 from Wattpad/aws-ca-bug-in…

…stance-not-in-known-group

AWS Cluster Autoscaler: NodeGroupForNode should return nil if instance is not in any known ASG

Merge pull request kubernetes-retired#1301 from mwielgus/add-null-han…

…dling-for-migconfigs

Cluster autoscaler: add handlign for nill mig configs (in case not all l node pools are autoscaled)

Merge pull request kubernetes-retired#1001 from stephenrlouie/common_…

…vars

refactor common

Merge pull request kubernetes-retired#1203 from eparis/yellow-e2e-status

Display when the test are 'yellow'

Merge pull request kubernetes-retired#850 from simonswine/feature-ssl…

…-redirect

ingress: adds configurable SSL redirect nginx controller

Merge pull request kubernetes-retired#647 from bprashanth/ing_docs

Clarify firewall rule doc.

Merge pull request kubernetes-retired#403 from eparis/whitelists

[submit queue] Update manual whitelists