I've been using Laravel for a while now. What you have looks like a snippet for the config/app.php config file.
All it's doing is returning an array. This is part of the Laravel configuration. You don't use it, Laravel does. If you need to change any configuration for Laravel, you'll do it in the php files under the config directory.
Like, if you are adding a plugin for Laravel, you'll install it through composer, and register it with Laravel using the app config.
Example:
Installing the Gravatar plugin for Laravel.
$ composer require thomaswelton/gravatar 1.*
And add the facade and service provider through the app.php config
<?php
return array(
...
'providers' => array(
'Thomaswelton\LaravelGravatar\LaravelGravatarServiceProvider'
...
'aliases' => array(
'Gravatar' => 'Thomaswelton\LaravelGravatar\Facades\Gravatar'
...
That's essentially all these files are for, is the configuration for Laravel.