204: Add User.current_login_* helper methods
204: Add User.current_login_* helper methods

User.current_login_age returns the time since the user's current login.

User.current_login_recent? returns whether the user's current login occurred
within the cutoff time (defaults to 60 minutes).

thecartercenter/elmo,thecartercenter/elmo,thecartercenter/elmo