Add pundit

Restrict access to certain profile show pages based on user roles. So for example if the current user is an admin, they can see more of the users in the directory than a person who is just a student or not logged in.
    helper_method :current_user

is what allows us to use `current_user` in the views now that we are no longer setting `@current_user`. Otherwise the method will only be available to the controller.