provision Kubelet config file for GCE

This PR extends the client-side startup scripts to provision a Kubelet
config file instead of legacy flags. This PR also extends the
master/node init scripts to install this config file from the GCE
metadata server, and provide the --config argument to the Kubelet.

cmd/kubelet/app/server.go

@@ -229,6 +229,7 @@ HTTP server: The kubelet can also listen for HTTP and respond to a simple API
 			}
 
 			// run the kubelet
+			glog.V(5).Infof("KubeletConfiguration: %#v", kubeletServer.KubeletConfiguration)
 			if err := Run(kubeletServer, kubeletDeps); err != nil {
 				glog.Fatal(err)
 			}