Fix register
Merge pull request #560 from liuchuangww/user

Fix register
Add last modify
Add last modified
Merge pull request #561 from liuchuangww/user

User
Change user data filed name
Merge pull request #562 from liuchuangww/user

Change user data filed name
Changed comment locate API params
Merge branch 'user' of https://github.com/pi-engine/pi into user
Added comment webservice API placeholder, not implemented yet.
Updated readme
Updated readme
Update README.md