Remove the word middleware (#1067)

* Rename middleware to plugin

first pass; mostly used 'sed', few spots where I manually changed
text.

This still builds a coredns binary.

* fmt error

* Rename AddMiddleware to AddPlugin

* Readd AddMiddleware to remain backwards compat

plugin/kubernetes/handler_pod_insecure_test.go

@@ -0,0 +1,59 @@
+package kubernetes
+
+import (
+	"testing"
+
+	"github.com/coredns/coredns/plugin/pkg/dnsrecorder"
+	"github.com/coredns/coredns/plugin/test"
+
+	"github.com/miekg/dns"
+	"golang.org/x/net/context"
+)
+
+var podModeInsecureCases = []test.Case{
+	{
+		Qname: "10-240-0-1.podns.pod.cluster.local.", Qtype: dns.TypeA,
+		Rcode: dns.RcodeSuccess,
+		Answer: []dns.RR{
+			test.A("10-240-0-1.podns.pod.cluster.local.	0	IN	A	10.240.0.1"),
+		},
+	},
+	{
+		Qname: "172-0-0-2.podns.pod.cluster.local.", Qtype: dns.TypeA,
+		Rcode: dns.RcodeSuccess,
+		Answer: []dns.RR{
+			test.A("172-0-0-2.podns.pod.cluster.local.	0	IN	A	172.0.0.2"),
+		},
+	},
+}
+
+func TestServeDNSModeInsecure(t *testing.T) {
+
+	k := New([]string{"cluster.local."})
+	k.APIConn = &APIConnServeTest{}
+	k.Next = test.NextHandler(dns.RcodeSuccess, nil)
+	ctx := context.TODO()
+	k.podMode = podModeInsecure
+
+	for i, tc := range podModeInsecureCases {
+		r := tc.Msg()
+
+		w := dnsrecorder.New(&test.ResponseWriter{})
+
+		_, err := k.ServeDNS(ctx, w, r)
+		if err != tc.Error {
+			t.Errorf("Test %d expected no error, got %v", i, err)
+			return
+		}
+		if tc.Error != nil {
+			continue
+		}
+
+		resp := w.Msg
+		if resp == nil {
+			t.Fatalf("Test %d, got nil message and no error for %q", i, r.Question[0].Name)
+		}
+
+		test.SortAndCheck(t, resp, tc)
+	}
+}