def add_measurement(key, options = {})
      if options.is_a?(Hash)
        self.measurements << Measurement.lookup(key).new(options)
      else
        self.measurements << options
      end
    end
def add_measurement(key, options = {})
      if options.is_a?(Hash)
        self.measurements << Measurement.lookup(key).new(options)
      else
        self.measurements << options
      end
    end
Add a measurement by its symbol name with options

 @param key [Symbol] any one of the measurable classes lookup key
 @param options [Hash or Object] for the measurement