Make CoreDNS build on Go 1.7 (#919)

.travis.yml

@@ -7,6 +7,7 @@ services:
 
 language: go
 go:
+  - 1.7
   - 1.8
 
 go_import_path: github.com/coredns/coredns

middleware/kubernetes/apiproxy.go

@@ -72,5 +72,5 @@ func (p *apiProxy) Run() {
 
 func (p *apiProxy) Stop() {
 	p.handler.Stop()
-	p.Close()
+	p.listener.Close()
 }