Handle K8s middleware NS record (#662)

* commit for testing in cluster

* commit for testing in cluster

* refactor and add ns.dns record

* Release 007

* reduce heap allocations

* gofmt

* revert accidental Makefile commits

* restore prior rcode for disabled pod mode

* revert Makefile deltas

* add unit tests

* more unit tests

* make isRequestInReverseRange easier to test

* more unit tests

* addressing review feedback

* commit setup.go

middleware/kubernetes/setup.go

@@ -51,8 +51,11 @@ func setup(c *caddy.Controller) error {
 }
 
 func kubernetesParse(c *caddy.Controller) (*Kubernetes, error) {
-	k8s := &Kubernetes{ResyncPeriod: defaultResyncPeriod}
-	k8s.PodMode = PodModeDisabled
+	k8s := &Kubernetes{
+		ResyncPeriod:   defaultResyncPeriod,
+		interfaceAddrs: &InterfaceAddrs{},
+		PodMode:        PodModeDisabled,
+	}
 
 	for c.Next() {
 		if c.Val() == "kubernetes" {