Fix Devise trackable integration

Devise counters sign_in_count, last_sign_in_at, current_sign_in_at
are no longer updated when authenticating with token. They however
keep being updated when signin in through `SessionsController#create`.

See https://github.com/plataformatec/devise/issues/953
and https://github.com/plataformatec/devise/blob/v3.2/lib/devise/hooks/trackable.rb#L6

Fixes #51