Remove support  for 5sing.com and add support for 5sing.kugou.com

Due to some reasons,the domain of 5sing.com has changed to 5sing.kugou.com,so the script is out of date.
And i found that the support of subdomain of you-get is incomplete ,so i just put the script under the name of kugou.I would try my best to complete the support of kugou.
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由于某些原因5sing已更换二级域名5sing.kugou.com，脚本失效。
以及发现you-get 对二级域名的支持有限，所以暂时把脚本放在kugou下面。
关于kugou主站部分我会尽力完成的。