add default service cluster ip range to --insecure-registry

This allows a kubelet to communicate with an in-cluster registry as
per https://github.com/kubernetes/minikube/blob/master/docs/insecure_registry.md

cmd/minikube/cmd/start.go

@@ -293,7 +293,7 @@ func init() {
 	startCmd.Flags().StringArrayVar(&dockerOpt, "docker-opt", nil, "Specify arbitrary flags to pass to the Docker daemon. (format: key=value)")
 	startCmd.Flags().String(apiServerName, constants.APIServerName, "The apiserver name which is used in the generated certificate for localkube/kubernetes.  This can be used if you want to make the apiserver available from outside the machine")
 	startCmd.Flags().String(dnsDomain, "", "The cluster dns domain name used in the kubernetes cluster")
-	startCmd.Flags().StringSliceVar(&insecureRegistry, "insecure-registry", nil, "Insecure Docker registries to pass to the Docker daemon")
+	startCmd.Flags().StringSliceVar(&insecureRegistry, "insecure-registry", []string{util.DefaultServiceClusterIP + "/24"}, "Insecure Docker registries to pass to the Docker daemon")
 	startCmd.Flags().StringSliceVar(&registryMirror, "registry-mirror", nil, "Registry mirrors to pass to the Docker daemon")
 	startCmd.Flags().String(kubernetesVersion, constants.DefaultKubernetesVersion, "The kubernetes version that the minikube VM will use (ex: v1.2.3) \n OR a URI which contains a localkube binary (ex: https://storage.googleapis.com/minikube/k8sReleases/v1.3.0/localkube-linux-amd64)")
 	startCmd.Flags().String(containerRuntime, "", "The container runtime to be used")