Modify DNSLink behavior to quickly return for any *.skynet URLs

[kwypchlo]

Currently, the extension pages still show as loading in the browser while it waits for the return from DNSLink. We should quickly return and not wait to avoid 4seconds of waiting (probably a 200 with a message saying this is reserved or that your extension isn't configured correctly).

[pcfreak30]

I am sort of doing this already for lume, and I plan on lume relays to handle this role which is a dummy node server that returns a status code defined in the request header. This thus solves the status code limitations firefox has in its webRequest API.