Patched the Symfony UploadedFile class

Hello,

Here's a patch for the `Symfony\Component\HttpFoundation\File\UploadedFile` class that has 2 required arguments (whereas `SplFileInfo` has one).
It's a quick POC, so unmergeable for now.

Just wanted to gather your thoughts about patching 3rd party library class (which could potentially open the pandora box!).

FYI, here's the error message when trying to double this class:

```
warning: Missing argument 2 for Symfony\Component\HttpFoundation\File\UploadedFile::__construct(), called in
/home/gildas/projects/pim/vendor/phpspec/prophecy/src/Prophecy/Doubler/Generator/ClassCreator.php(49) :
eval()'d code on line 6 and defined in
/home/gildas/projects/pim/vendor/symfony/symfony/src/Symfony/Component/HttpFoundation/File/UploadedFile.php line 92
```

Cheers!

**EDIT**
Yes, PRs #99, #98 and this one are related :wink: