The only place it was used was in window.onpageunload, and we have a
better way of determining if the proxy is active there (through the ui).
I also removed that code from the webextension since the proxy won't
stop running unless you close the browser and after testing it looks
like that code doesn't notify the user anyway.
Some files were omitted in the .eslintignore, left as an exercise to the
reader.
We probably want to reduce amount of globals overall and use proper es
modules.
