Update CamelotAuthServiceProvider.php

It is necessary to verify the existance of ENVIRONMENT constant in order to run unit tests properly.

1) UploadHelperTest::testSaveNewFile
ErrorException: Constant ENVIRONMENT already defined

C:\wamp\www\sample_domain\laravel\vendor\t4s\camelot-auth\src\T4s\CamelotAuth\CamelotAuthServiceProvider.php:56
C:\wamp\www\sample_domain\laravel\vendor\laravel\framework\src\Illuminate\Foundation\Application.php:318
C:\wamp\www\sample_domain\laravel\vendor\laravel\framework\src\Illuminate\Foundation\ProviderRepository.php:82
C:\wamp\www\sample_domain\laravel\vendor\laravel\framework\src\Illuminate\Foundation\start.php:210
C:\wamp\www\sample_domain\laravel\bootstrap\start.php:62
C:\wamp\www\sample_domain\laravel\app\tests\TestCase.php:16
C:\wamp\www\sample_domain\laravel\vendor\laravel\framework\src\Illuminate\Foundation\Testing\TestCase.php:42
C:\wamp\www\sample_domain\laravel\vendor\laravel\framework\src\Illuminate\Foundation\Testing\TestCase.php:31
C:\wamp\bin\php\php5.4.12\pear\PHPUnit\TextUI\Command.php:176
C:\wamp\bin\php\php5.4.12\pear\PHPUnit\TextUI\Command.php:129