Cherry-Pick: GKE Integration Support into Release-0.5.X#314

Merged

k8s-ci-robot merged 2 commits intokubernetes-sigs:release-0.5.0from

hantaowang:gke-integration-tests

Jun 24, 2019

Commits on Jun 7, 2019

add ability to use gcloud to boot a gke cluster for e2e integration
Hantao (Will) Wang
committed

Commits on Jun 24, 2019

add ability to set cluster and kube version in integration script
Hantao (Will) Wang
committed