获取下载日志游标

GET /cursor?topic_id=xxxxxxxx-xxxx-xxxx-xxxx&start=2017-12-28%2014%3A13%3A00 HTTP/1.1
Host: <Region>.cls.tencentyun.com
Authorization: <AuthorizationString>

GET /cursor

HTTP/1.1 200 OK
Content-Type: application/json
Content-Length: 23

{
    "cursor": "1212ssssxxxxxx"
}