FatalErrorException in StripeBilling.php line 19: Class 'Stripe' not found

I'm using Laravel 5.2.

The class is in the files with the namespace of stripe, I'm just confused as to why it can't find the Stripe class.

composer.json

"require": {
        "php": ">=5.5.9",
        "laravel/framework": "5.2.*",
        "illuminate/html": "^5.0",
        "stripe/stripe-php": "3.9.0"
}

StripeBilling.php is pretty much the exact same as the Laracast series on stripe:

https://github.com/laracasts/Billing-With-Stripe/blob/master/app/Acme/Billing/StripeBilling.php

Thanks for any help I get.