etcdctl: Add support for formating output of key related commands

All v2 key and dir related commands will now honor the global format option if
it was specified. Otherwise, the output will remain the same.

etcdctl/ctlv2/command/mkdir_command.go

@@ -48,9 +48,12 @@ func mkdirCommandFunc(c *cli.Context, ki client.KeysAPI, prevExist client.PrevEx
 	ttl := c.Int("ttl")
 
 	ctx, cancel := contextWithTotalTimeout(c)
-	_, err := ki.Set(ctx, key, "", &client.SetOptions{TTL: time.Duration(ttl) * time.Second, Dir: true, PrevExist: prevExist})
+	resp, err := ki.Set(ctx, key, "", &client.SetOptions{TTL: time.Duration(ttl) * time.Second, Dir: true, PrevExist: prevExist})
 	cancel()
 	if err != nil {
 		handleError(ExitServerError, err)
 	}
+	if c.GlobalString("output") != "simple" {
+		printResponseKey(resp, c.GlobalString("output"))
+	}
 }