Preserve file relative path & name during PHP_CodeSniffer analyzer run

1. I'm not sure it that is covered by tests at 100%, because the `$file->getPath()` always resulted in `Foo.php` without relative path. I have added a test however, that will exclude one sniff based for a `Foo.php` file. This way if that breaks at some point, then we'll have failing test.
2. I've used `shell_exec` to recursively remove a directory and because of it won't work on Windows.

Closes #201