SmartplugV2 EnergyV2: loosen up requirement for energy sensor.
This is quite a full featured smartplug, and would match many more models
if the energy sensor and calibration values were optional, as many smartplugs
do not always return those.
Issue #1409
- this smartplug contains 3 extra unsupported values: overcharge protection, inching and random timer, the latter 2 of which are complex encodings that cannot be supported. But for now, this is a better match than the Aubess 1-gang switch it currently matches.