changes for 7.0


/*
1:
  arr.createNestedArray();                        ->    arr.add<JsonArray>();
  arr.createNestedObject();                       ->    arr.add<JsonObject>();
2:
  config.createNestedArray("device");             ->    config["device"].to<JsonArray>(); 
  config.createNestedObject("device")             ->    config["device"].to<JsonObject>()
*/