gcr.io:获取gcr docker映像 源码

使用travis同步gcr.io和quay.io的docker镜像 GOOLE_NAMESPACE: google-appengine cloudsql-docker cloud-marketplace kubeflow-images-public spinnaker-marketplace istio-release kubernetes-e2e-test-images cloud-builders knative-releases cloud-datalab linkerd-io distroless google_containers kubernetes-helm runcondu