Add SyncPod() to DockerManager and use in Kubelet.

This allows us to abstract away the logic of syncing a pod by the
runtime. It will allow other runtimes to perform their own sync as well.

pkg/kubelet/dockertools/manager_test.go

@@ -47,6 +47,9 @@ func NewFakeDockerManager() (*DockerManager, *FakeDockerClient) {
 		0, 0, "",
 		kubecontainer.FakeOS{},
 		networkPlugin,
+		nil,
+		nil,
+		nil,
 		nil)
 
 	return dockerManager, fakeDocker