Merge branch 'login_warning' of https://github.com/Cal-CS-61A-Staff/ok into login_warning

* 'login_warning' of https://github.com/Cal-CS-61A-Staff/ok:
  Moved logic to the frontend.
  Added warning dialog for logging in with a non-Berkeley email.
force account chooser
merge url chooser
Merge branch 'master' of https://github.com/Cal-CS-61A-Staff/ok into login_chooser

* 'master' of https://github.com/Cal-CS-61A-Staff/ok:
  Moved logic to an angular controller, and fixed logic.
Merge pull request #244 from Cal-CS-61A-Staff/login_chooser

Force users to go to the account chooser.