Fixed training slashed with log files path in Windows

There was an error when trying to obtain the path to the log files in Windows.
The code
<pre>
    str_replace($path, null, $this->app['path.storage'])
</pre>
was not running well in Windows due to the fact that $path is "C:\wamp\www/" and $this->app['path.storage'] is "C:\wamp\www\app\storage".

The fixed forces all the paths to use forward slashes.