Merge Add-on and Standalone modes

[GeoDerp]

Discussion starting in: https://github.com/davidusb-geek/emhass/issues/262 EMHASS is probably in a sate where we could choose to use the local or external HA API automatically based on API key (SUPERVISOR_TOKEN). Removing the need of passing it via arguments. Allowing for both Standalone and Add-on modes to merged into one.

This may be something I'll look into when I have some time. I am sure all help will be appreciated.