def register(action, max, period)
      @limits ||= {}
      @limits[action.to_sym] = { max: max, period: period }
    end
def register(action, max, period)
      @limits ||= {}
      @limits[action.to_sym] = { max: max, period: period }
    end
Register a default cap and period with an action name. For use with
 {TrafficJam.limit}.

 @param action [Symbol] action name
 @param max [Integer] limit cap
 @param period [Fixnum] limit period in seconds