请支持mass/delete，群发消息删除接口

[j5land]

请支持mass/delete，群发消息删除接口
https://mp.weixin.qq.com/wiki?action=doc&id=mp1481187827_i0l21#4

http请求方式: POST
https://api.weixin.qq.com/cgi-bin/message/mass/delete