Merge pull request #3 from waipbmtd/master

添加获取首日，7日，30日新增留存方法
update setup.py
update setup.py
Merge pull request #4 from waipbmtd/master

支持dru(每日付费用户),mru(每月付费用户)
Merge remote-tracking branch 'dwarf_camel/master'