Externalize configuration for Home Assistant

[scaiandre]

Congrats for this great solution! It works very good with my setup!

I'm running it now as a Home Assistant ( https://www.home-assistant.io/ ) addon. If you have that, you could check that out from here: https://github.com/scaiandre/hassio-artnet-addon-repository

But to make this work, I need all the configuration, especially the entertainmentRoom and the lights setup, to reside in the configuration file.

Also, since it is running in its own Docker container, the solution needs to determine its own ip address to listen on.

Furthermore, since it is running in a static Docker container, there is no command line to run the solution from, I allowed the actual command to run ("run", "pair", etc.) to also be placed into the configuration file and added a command line option "from-config".

I made these changes in the attached pull request. I hope you find the changes meaningful enough to integrate.

In my Home Assistant solution I have switch on the wall, which now either starts the Add On running this solution and all DMX stuff (LightRider, Showtec NET-2 Artnet bridge). After that, all my various Hue lights attached to the configured Entertainment Room go into DMX mode. When I flick back the switch, everything is stopped again.

Works super nice! Thank you for your work!