missing roles value

I guess this isn't the best solution, cause it mark as hard code right now.
https://github.com/linnovate/mean/blob/master/server/controllers/users.js#L61

But it should also add on the oauth callback in current version (0.3.3), 
cause the missing roles value will make global.authenticated error.
(ex. topbar will keep showing register and login even user already login with oauth)