cleanups: go vet/golint (#331)

Go vet and golint the new code once again.

Drop Name from NameTemplate - it's cleaner: nametemplate.Template.

middleware/pkg/response/classify.go

@@ -68,6 +68,4 @@ func classify(t Type) Class {
 	default:
 		return Error
 	}
-	// never reached
-	return All
 }

middleware/pkg/response/typify.go

@@ -10,7 +10,7 @@ import (
 type Type int
 
 const (
-	// Success indicates a positive reply
+	// NoError indicates a positive reply
 	NoError Type = iota
 	// NameError is a NXDOMAIN in header, SOA in auth.
 	NameError