Does not list all scripts

It looks like `npe scripts` is not listing out all scripts files.

```
$ npe scripts
{ test: 'mocha' }
$ cat package.json | grep scripts -A 1
  "scripts": {
    "build": "npm run download_translations && grunt build",
```

Upon deeper inspection, it looks like this is because it is using `npe's __dirname` as the default directory whereas the README implies it is for the working directory (`process.cwd()`). 

https://github.com/zeke/npe/blob/009255d99c88455b7c34e61bf2f73507557bceab/index.js#L9-L11