Increased required realpath_cache_size on Windows
Increased required realpath_cache_size on Windows

Incorrectly set `realpath_cache_size` causes quite big speed degradation
 on Windows systems (like really big!).

The realpath_cache_size in the `php.ini` is *total number of bytes in the
path strings stored + metadata*
(see http://php.net/manual/en/ini.core.php#ini.realpath-cache-size).
So if the requirement is set to 1024 (which means 1024B), only 10-20
paths would fit there.

Just to get some idea about optimal value, I set really high limit in
`php.ini` and added `realpath_cache_size()` call in the `BlogController` of
 the Symfony demo app (it fetches the currently used cache size). The
value fluctuated around 500 000. Homepage of Sylius consumed around
1 500 000. As I had those var_dumps in the controller, more was probably
 consumed during the request. Therefore, I suggest using 5000k as
 a recommended value. It should be enough for even big Symfony projects.

I did just a very basic performance testing with admin of Symfony demo app:
* with `realpath_cache_size` set to 1000 takes 500-600ms to load
* with `realpath_cache_size` set to 5000k takes 100-200ms to load
(tested only with browser, changed the value in php.ini, restarted Apache)

And with Sylius homepage:
* with `realpath_cache_size` set to 1000 takes 16s to load (yeah, seconds)
* with `realpath_cache_size` set to 5000k takes 2s to load

HeahDude/SensioDistributionBundle,HeahDude/SensioDistributionBundle,sensiolabs/SensioDistributionBundle,sensiolabs/SensioDistributionBundle