Additions and enhancements (#14)

- add interactive API repl
- enhance cluster status output (use -v)
- add more ccr commands
- refactoring

pkg/es/cluster_util.go

@@ -375,6 +375,16 @@ func getClusterData(es *elasticsearch.TypedClient, wg *sync.WaitGroup, reschan c
 		ar.ccr = res
 		ar.which = ResponseCcr
 		arerr = err
+
+	case "stats":
+		res, err := es.Cluster.Stats().
+			Header("content-type", "application/json").
+			Header("accept", "application/json").
+			Do(context.Background())
+
+		ar.stats = res
+		ar.which = ResponseStats
+		arerr = err
 	}
 
 	if arerr != nil {