Parameterise location of config files

[mausch]

Hi and thanks for this project!

It looks like config.json and devices.json are currently only loaded from the same directory as the binary?
In a Linux FHS binaries go to e.g. /usr/bin and config goes to /etc with maybe the possibility of overriding from ~/.config .
Maybe wolweb could add a cmdline parameter to set the location of config files.