Set reason and message on Pod during nodecontroller eviction

Pods which are evicted by the nodecontroller due to network
malfunction, or unresponsive kubelet should be differentiated
from termination initiated by other sources. The reason/message
are consumed by kubectl to provide a better summary using get/describe.

pkg/util/node/node.go

@@ -31,6 +31,13 @@ import (
 	"k8s.io/kubernetes/pkg/types"
 )
 
+const (
+	// The reason and message set on a pod when its state cannot be confirmed as kubelet is unresponsive
+	// on the node it is (was) running.
+	NodeUnreachablePodReason  = "NodeLost"
+	NodeUnreachablePodMessage = "Node %v which was running pod %v is unresponsive"
+)
+
 func GetHostname(hostnameOverride string) string {
 	var hostname string = hostnameOverride
 	if hostname == "" {