Merge pull request #242 from Cal-CS-61A-Staff/login_warning

Adds a login warning for non-Berkeley emails.
Made login warning run only once.
merge url chooser
Moved logic to an angular controller, and fixed logic.
Merge pull request #243 from Cal-CS-61A-Staff/login_warning_fix

Made login warning run only once.
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.