Update minimum supported kubernetes to 1.11

Summary

GKE has already deprecated 1.10, (and is right now deprecating 1.11) and EKS will be deprecating 1.10 on July 22nd https://docs.aws.amazon.com/eks/latest/userguide/kubernetes-versions.html (And Kubernetes itself no longer supports 1.10)

We should update our min supported version to 1.11, and update all our kubectl related tools to 1.12.

Note that due to version support for the kube tools, we typically need to update our tooling in order to support the newer releases. Using the 1.12 tooling allows us to support 1.11, 1.12, and 1.13. https://kubernetes.io/docs/setup/release/version-skew-policy/#kubectl

Tasks

Edited by Jason Plum