Implement http stats.

plugins/elasticsearch/elasticsearch.go

@@ -23,6 +23,7 @@ type node struct {
 	Network    interface{}       `json:"network"`
 	FS         interface{}       `json:"fs"`
 	Transport  interface{}       `json:"transport"`
+	HTTP       interface{}       `json:"http"`
 }
 
 const sampleConfig = `
@@ -127,6 +128,9 @@ func (e *Elasticsearch) gatherUrl(url string, acc plugins.Accumulator) error {
 		if err := e.parseInterface(acc, "transport", tags, n.Transport); err != nil {
 			return err
 		}
+		if err := e.parseInterface(acc, "http", tags, n.HTTP); err != nil {
+			return err
+		}
 	}
 
 	return nil