before_filter :admin_only, :except=>[:roster, :manually_enroll, :manually_withdraw, :manually_enroll_waiting_list, :manually_remove_from_waiting_list, :update_att]
  before_filter :presenter_only, :only=>[:roster, :manually_enroll, :manually_withdraw, :manually_enroll_waiting_list, :manually_remove_from_waiting_list, :update_att]
  before_filter :require_offering, :only=>[:new, :create]
  before_filter :find_workshop, :except=>[:new, :create, :adminlist]
  before_filter :check_term, :only=>[:new, :create]