I have a customer that needs a static ip set on a resin.io powered device. I know that this is really straightforward and also very well documented in the following blog post. https://resin.io/blog/how-to-configure-a-static-ip-address-with-resin-io/ - but the customer also provided me a proxy setting but I have no clue how to set proxy settings within the config.json. Is this possible? I am looking for some sample config.json for the proxy part.