Stub npm start script

Nobody has claimed this yet.

It'd be nice, when **prot** stubs out the `package.json`, to add a `"start"` script to the `"scripts"` block as well.

In fact, it'd be extra nice if I started it with:

```
$ prot index.js --css main.css --install --react
```

It would generate:

`./package.json`

``` json
{
"name": "prot-test",
"version": "1.0.0",
"description": "",
"main": "index.js",
"scripts": {
"start": "prot index.js --css main.css --install --react",
"test": "echo \"Error: no test specified\" && exit 1"
},
"license": "MIT",
"dependencies": {}
}
```

Note: The "start" script would be the same command as I used to start with.

Start at the code that stubs package.json when prot is invoked with the documented index.js, CSS, install, and React options. Update the generated scripts block so it includes the same prot command as a start script, then verify the generated package.json matches the example in this issue.

Written by the indexing model from the issue text.