给后端代码整理注释。
Merge remote-tracking branch 'origin/dev' into dev-iron
Merge pull request #42 from FeverTeam/dev

Dev
Merge branch 'dev-iron' of https://github.com/FeverTeam/LivePPT-Play2 into dev-iron
给获取PPT图像提供用户权限限制
修复上一次push的bug
增加用户修改密码接口
修复几个bug，包括昨晚俊浩说的线上会议发起接口不成功的问题。
Merge pull request #43 from FeverTeam/dev-iron

Dev iron