feat(coreos-base/oem-gce): Add a message about the cloud sdk container

Since it isn't simple for us to provide the Python based Google Cloud
SDK tools users should be directed to the Docker container instead.

Also fix the bug report URL, not that anyone looks at it... :)

sdk_container/src/third_party/coreos-overlay/coreos-base/oem-gce/files/cloud-config.yml

@@ -106,4 +106,23 @@ coreos:
       id: gce
       name: Google Compute Engine
       home-url: https://cloud.google.com/products/compute-engine/
-      bug-report-url: https://github.com/coreos/coreos-overlay
+      bug-report-url: https://github.com/coreos/bugs/issues
+
+write_files:
+  - path: /etc/profile.d/google-cloud-sdk.sh
+    permissions: 0644
+    content: |
+        #!/bin/sh
+        function _fake_gcloud {
+        cat >&2 <<EOF
+        gcloud, gcutil, and other Google Cloud SDK tools are available from
+        Google via a Docker container named google/cloud-sdk.
+
+        See https://index.docker.io/u/google/cloud-sdk/
+        EOF
+        return 1
+        }
+
+        alias gcloud=_fake_gcloud
+        alias gcutil=_fake_gcloud
+        alias gsutil=_fake_gcloud