Support scripts' folders

Add the capability to read and run script in a subfolder : 

```
files
— ...
scripts
— clean-install.sh
— update-cask.js
— update-pkg
    — index.sh
    — root.sh
    — close.sh
```

With this file tree, configfile will read the `update-pkg` folder as only one scripts and will automatically run `update-pkg/index.sh`. This starting file might use other file in this folder.


