Add debug_update_logging_config rpc method that reloads current logging configuration. To use this command, update your config.json, then execute this command to update logging. Note that due to problems with current fc::ofstream support, this truncates the most recent log file(this is also why the most recent log is deleted when you restart the client). Planning to look into fc:ofstream  next to see if this can be cleaned up gracefully so that we don't lose logging.