Update user.js

[amdacccache]

log out issues

[Ziqing19]

The authentication router is the one that visitor can also access. The other two are user-only, and will send 403 if a visitor try to access them (please check the checkLogStatus() function).
The /user/logout router just destorys the user session in the server and let client do the redirect. And of course a visitor cannot log out. That is why this router is in user.js.