Merge pull request #423 from liuchuangww/user

Fix delete avatar
Completed post comments list page
Merge pull request #424 from linzongshu/user

Completed post comments list page and added two batch operation action in back-end
User log page and user old code clean up
Merge pull request #425 from sexnothing/user

User log page and user old code clean up
Unified user model
Moved role management to user module from system module
Refactored mail config