Add prepublish script
Add prepublish script

This runs before `npm publish` and before `npm link`. It may save you from
accidentally pushing a bad version to npm, and it lets other developers
contribute more easily.

```
cd ~/repos/fetch-it
npm link

cd ~/repos/my-other-project
npm link fetch-it
```

https://docs.npmjs.com/cli/link

dig3/fetch-it,tryolabs/fetch-it,Touna-App-Front-End/fetch-it,tryolabs/fetch-it,Touna-App-Front-End/fetch-it,dig3/fetch-it