Add an option to install kubectl

Would be useful if we don't have Kubernetes locally installed.

Change-Id: Ia9621a738e44d9078251fb9f4b8761d73f011104
diff --git a/metadata/service/client.yml b/metadata/service/client.yml
index 6349fc0..512e99a 100644
--- a/metadata/service/client.yml
+++ b/metadata/service/client.yml
@@ -13,5 +13,10 @@
         install: true
         namespace: kube-system
         host:
+      kubectl:
+        install: false
+        download_url: https://dl.k8s.io/v1.6.7/kubernetes-client-linux-amd64.tar.gz
+        download_hash: sha256=54947ef84181e89f9dbacedd54717cbed5cc7f9c36cb37bc8afc9097648e2c91
+        tarball_path: kubernetes/client/bin/kubectl
       repos: {}
       releases: {}