Introduce SystemContainer to Kubelet ContainerManager.

This generalizes the handling of containers in the
ContainerManager.

Also introduces the ability to determine how much
resources are reserved for those system containers.

pkg/kubelet/kubelet.go

@@ -301,7 +301,7 @@ func NewMainKubelet(
 
 	// Setup container manager, can fail if the devices hierarchy is not mounted
 	// (it is required by Docker however).
-	containerManager, err := newContainerManager(dockerDaemonContainer, systemContainer)
+	containerManager, err := newContainerManager(dockerDaemonContainer, systemContainer, resourceContainer)
 	if err != nil {
 		return nil, fmt.Errorf("failed to create the Container Manager: %v", err)
 	}