mw/kubernetes: resync to opts (#957)

* mw/kubernetes: resync to opts

Only used to initialize the cache that already has a dnsControlopts, so
remove it from the main kubernetes struct.

* Fix test

* mw/kubernetes: LabelSelector to options as well

Labels select is also only used for init. Don't carry it in the main
kubernetes struct.

* remove this test: can't happen

Caddyfile parser will only call setup when it sees kubernetes.

* erge gone wrong

middleware/kubernetes/setup_reverse_test.go

@@ -17,7 +17,7 @@ func TestKubernetesParseReverseZone(t *testing.T) {
 
 	for i, tc := range tests {
 		c := caddy.NewTestController("dns", tc.input)
-		k, err := kubernetesParse(c)
+		k, _, err := kubernetesParse(c)
 		if err != nil {
 			t.Fatalf("Test %d: Expected no error, got %q", i, err)
 		}