给后端代码整理注释。
Merge pull request #40 from FeverTeam/dev-cold

Dev cold
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
1、将/ppt/pageImage 接口的uemail和token字段从header改为GET参数传入；2解决token可能存在空指针导致toLowerCase的出错。
Merge pull request #46 from FeverTeam/dev-iron

1、将/ppt/pageImage 接口的uemail和token字段从header改为GET参数传入；2解决token可能存在空指针导致toL...
Merge pull request #45 from FeverTeam/dev

Dev