Google_Auth_AssertionCredentials class not found

[stechnique]

Getting this error after installation on Laravel 4.2 when using gcloud storage:

PHP Fatal error: Uncaught Error: Class 'Google_Auth_AssertionCredentials' not found in /[...]/vendor/superbalist/laravel4-storage/src/StorageAdapterFactory.php:75
Stack trace:
#0 /[...]/vendor/superbalist/laravel4-storage/src/StorageAdapterFactory.php(103): Superbalist\Storage\StorageAdapterFactory::make('gcloud')
#1 /[...]/vendor/superbalist/laravel4-storage/src/StorageServiceProvider.php(16): Superbalist\Storage\StorageAdapterFactory::makeCached('gcloud')
#2 /[...]/vendor/laravel/framework/src/Illuminate/Container/Container.php(501): Superbalist\Storage\StorageServiceProvider->Superbalist\Storage{closure}(Object(Illuminate\Foundation\Application), Array)
#3 /[...]/vendor/laravel/framework/src/Illuminate/Container/Container.php(428): Illuminate\Container\Container->build(Object(Closure), Array)
#4 /[...]/vendor/laravel/framework/src/Illuminate/Foundation/Application.php(462): Illuminate\Container\Con in /Users/lppapillon/dev/proxi/vendor/superbalist/laravel4-storage/src/StorageAdapterFactory.php on line 75

This is an update made on the google/auth package, I have tracked back to this issue here:
Superbalist/flysystem-google-cloud-storage#26
However this doesn't work in the laravel4-storage version. Could it be made to use a newer version of flysystem-google-storage, or an older version of google/auth perhaps?
Thanks!