Insecure resources warning from new Electron versions

I believe this is because the new Electron doesn't like to read things over HTTP, but I now see these warnings in the console on startup:

```
Electron Security Warning (Insecure Resources) This renderer process loads resources using insecure
protocols.This exposes users of this app to unnecessary security risks.
Consider loading the following resources over HTTPS or FTPS.
- http://localhost:9080/renderer.js
- http://localhost:9080/styles.css


For more information and help, consult
https://electronjs.org/docs/tutorial/security.
This warning will not show up
once the app is packaged.
```

Probably the right thing here is to disable this warning for content served out of localhost in development mode but... I'm not positive about that so I'm reluctant to wade in and change things.