Stop using dockerfile/* images

As per
http://blog.docker.com/2015/03/updates-available-to-popular-repos-update-your-images/
docker has stopped answering dockerfile/redis and dockerfile/nginx.  Fix all
users in our tree.  Sadly this means a lot of published examples are now broken.

examples/nfs/nfs-web-pod.yaml

@@ -9,7 +9,7 @@ metadata:
 spec:
   containers:
     - name: web
-      image: dockerfile/nginx
+      image: nginx
       ports:
         - name: web
           containerPort: 80