Fixes #53 SplFileInfo doesn't throw exception

The `_make_directory` function was failing due to an unused resource object.

Also, I couldn't find any evidence of PHP ever throwing an exception on `mkdir`, but I [left it in](https://github.com/kohana/cache/blob/3.3/master/classes/Kohana/Cache/File.php#L75-L89) just in-case.


That's exactly what I thought, @acoulton . I initially did not mind this for 3.4, and was going to merge this anyway, after I reviewed it today. But then the Drupal solution came up when I was digging what was `$context` used for.

So you want this to be different between 3.3 and 3.4? Or maybe @rafi you could kindly solve this the Drupal way and PR towards 3.3/develop?