Introduce

nsq_to_file只是一个普通的消费者，获取消息缓存到磁盘
topic 和 channel名字是否合法：

var validTopicChannelNameRegex = regexp.MustCompile(`^[\.a-zA-Z0-9_-]+(#ephemeral)?$`)
func IsValidTopicName(name string) bool {
    return isValidName(name)
}

// IsValidChannelName checks a channel name for correctness
func IsValidChannelName(name string) bool {
    return isValidName(name)
}

func isValidName(name string) bool {
    if len(name) > 64 || len(name) < 1 {
        return false
    }
    return validTopicChannelNameRegex.MatchString(name)
}