Adds FHEM support to OctoPrint-PSUControl as a sub-plugin

This plugin makes an FHEM device usable for PSU Control. Currently this is targeted at switch-like devices, i.e. sending set <device> on and set <device> off. While there is a certain amount of configuration available, I have only tested it using switches like the above.

Please check the github repo for up to date information and more details

Pictures

View of a switch-like device in FHEM
Screenshot of plugin settings page