Detect Zend OPcache and WinCache as PHP Accelerators

Now opcache, wincache shows "OK" as PHP Accelerators (when present and enabled)
Updated check method, cloning the funcionality used in HttpKernel (ConfigDataCollector.php)

The same fix should be made in:
Repository: sensiolabs/SensioDistributionBundle
File: Resources/skeleton/app/SymfonyRequirements.php

To avoid the recomendation triggered by:
```php
$this->addRecommendation(
	file_get_contents(__FILE__) === file_get_contents(__DIR__.'/../vendor/sensio/distribution-bundle/Sensio/Bundle/DistributionBundle/Resources/skeleton/app/SymfonyRequirements.php'),
	'Requirements file should be up-to-date',
	'Your requirements file is outdated. Run composer install and re-check your configuration.'
);
```