Menu breaks when opts.extra is not set

I was trying out the master branch of [makemehapi](https://github.com/spumko/makemehapi) and found that selecting any of the menu options resulted in this error:

```
/usr/local/lib/node_modules/makemehapi/node_modules/workshopper/menu.js:63
    if (opts.extras.indexOf(name.toLowerCase()) != -1)
                    ^
TypeError: Cannot call method 'indexOf' of undefined
```

This could just be a bug in makemehapi, but since menu.js contained a different conditional  at line 41 which checked for `opts.extras` before acting on it, I figured that `opts.extras` shouldn't be assumed.

Feel free to close out if I'm wrong.