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/setup_reverse_test.go

@@ -0,0 +1,35 @@
+package kubernetes
+
+import (
+	"testing"
+
+	"github.com/mholt/caddy"
+)
+
+func TestKubernetesParseReverseZone(t *testing.T) {
+	tests := []struct {
+		input         string   // Corefile data as string
+		expectedZones []string // expected count of defined zones.
+	}{
+		{`kubernetes coredns.local 10.0.0.0/16`, []string{"coredns.local.", "0.10.in-addr.arpa."}},
+		{`kubernetes coredns.local 10.0.0.0/17`, []string{"coredns.local.", "10.0.0.0/17."}},
+	}
+
+	for i, tc := range tests {
+		c := caddy.NewTestController("dns", tc.input)
+		k, _, err := kubernetesParse(c)
+		if err != nil {
+			t.Fatalf("Test %d: Expected no error, got %q", i, err)
+		}
+
+		zl := len(k.Zones)
+		if zl != len(tc.expectedZones) {
+			t.Errorf("Test %d: Expected kubernetes to be initialized with %d zones, found %d zones", i, len(tc.expectedZones), zl)
+		}
+		for i, z := range tc.expectedZones {
+			if k.Zones[i] != z {
+				t.Errorf("Test %d: Expected zones to be %q, got %q", i, z, k.Zones[i])
+			}
+		}
+	}
+}