Support asset versioning

[dmason30]

Fixes #31

    /*
    |--------------------------------------------------------------------------
    | Versioning
    |--------------------------------------------------------------------------
    |
    | Enable versioning of generated assets. This will append a query string
    | to the asset path with a unique value based on the file content. This
    | is done by generating a manifest file that maps the original path to
    | the versioned path.
    |
    | Note: This feature requires the `manifest.json` file to be readable in
    | the public directory.
    |
    */
    'version' => [
        'enabled' => false,

        'manifest' => '/vendor/nova-tools/manifest.json',
    ],