plugin/kubernetes: Add upstream @self and loop count (#1484)

* add upstream @self and loop count

* 1st round of feedback

* allow argless upstream

* update test

* readmes

* feedback

request/request.go

@@ -9,6 +9,7 @@ import (
 	"github.com/coredns/coredns/plugin/pkg/edns"
 
 	"github.com/miekg/dns"
+	"golang.org/x/net/context"
 )
 
 // Request contains some connection state and is useful in plugin.
@@ -19,6 +20,8 @@ type Request struct {
 	// Optional lowercased zone of this query.
 	Zone string
 
+	Context context.Context
+
 	// Cache size after first call to Size or Do.
 	size int
 	do   int // 0: not, 1: true: 2: false