Thanks for the feedback, I have merged your pull request into the code.
The mPower outlets are also sold in europe, since I live in Germany I only have the european versions. The problem is that the US-version only supports 110 Volt devices while the EU-Version only supports 220 Volt devices. Further, the EU Pro-Version has only 6 ports compared to the 8 ports of the US Pro-Version but aside from the volt limitations and the different socket types they look identical.
There are also very interesting in-wall outlets and power switches in the Ubiquiti mPower series (https://www.ubnt.com/mfi/inwall/) which seam to support the same API as the other mPower outlets and it looks to me that the in-wall switches can be used with my plugin with minimal changes. But unfortunately, they are only available in the 110 Volt US-version, I hope that these products will also come to the european market in a special 220 Volt version.