Remove token authentication.

We will use regular server sessions/cookies and oauth if required.
create new backbone models for devise3
Update currentUser after login/logout.
Set view model to currentUser and remove unused userName parameter.
Remove some dead code in application controller.
Set version number for devise.
Use new user registration model for sign up.
Explicitly set allowed request methods to make devise accept json (see https://github.com/plataformatec/devise/issues/2209) and by usin
Cleanup api signin/signout helpers (they are actually just json calls to devise).

- Also disable session spec for now as devise json login cannot be tested like this with spec.