Re-enable "net" connections when running under Electron

[KyleMaas]

I decided to try converting this to an Electron app. Despite never having built anything using Electron, it actually seems to work reasonably well. See:

https://github.com/KyleMaas/ssb-browser-demo-desktop

One thing about this though is that Electron's supposed to support generic socket connections just like Node.js. It would be nice if there was some way to detect that so that we could disable that error message blocking users from using net connections.