add envsubst for injected into .kube/config file

Dockerfile

@@ -1,2 +1,8 @@
 FROM alpine
-ADD https://storage.googleapis.com/kubernetes-release/release/v1.3.6/bin/linux/amd64/kubectl kubectl
+
+RUN apk add --update libintl && \
+    apk add --virtual build_deps gettext &&  \
+    cp /usr/bin/envsubst /usr/local/bin/envsubst && \
+    apk del gettext
+RUN mkdir /root/.kube
+ADD https://storage.googleapis.com/kubernetes-release/release/v1.4.1/bin/linux/amd64/kubectl kubectl

README.md

@@ -0,0 +1,8 @@
+### kubectl
+
+Contains the kubectl command for running against kubernetes.
+
+This also contains envsbst for setting up the `~/.kube/config` by injecting
+environment variables. This allows for injection of secrets into the config
+file without the secrets being shown in plain text, allowing them to be part
+of a CI/CD pipeline who's output is visible.