[SecurityBundle] Fix execution of functional tests with different names

Using "securitybundletest" as the default environment for the functional test's kernel causes a PHP fatal error redeclaring the class "appSecuritybundletestDebugProjectContainer" when multiple tests (with unique names) are executed. In lieu of forcing tests to specify their own environment explicitly, we can simply append the test name into the environment.

Note: this bug may be related to PHPUnit executing multiple tests within the same process.

src/Symfony/Bundle/SecurityBundle/Tests/Functional/WebTestCase.php

@@ -60,7 +60,7 @@ class WebTestCase extends BaseWebTestCase
         return new $class(
             $options['test_case'],
             isset($options['root_config']) ? $options['root_config'] : 'config.yml',
-            isset($options['environment']) ? $options['environment'] : 'securitybundletest',
+            isset($options['environment']) ? $options['environment'] : 'securitybundletest' . strtolower($options['test_case']),
             isset($options['debug']) ? $options['debug'] : true
         );
     }