Pump energy stats

[arieltools]

Hi! Awesome integration.

Here's one enhancement for pumps:

https://www.home-assistant.io/more-info/statistics/

It could be easily migrated to other devices as well.

[Crewski]

Are the pump sensor not working when you are trying to do statistics? I have all of them set to a state class of "measurement".

    @property
    def state_class(self):
        """State class of the sensor"""
        return SensorStateClass.MEASUREMENT