Currently the adapter only works with filesystem paths, I think we need to change the whole adapter then.

I added some more documentation in the code:

"Gaufrette uses a key to identify a file or directory. This adapter uses a filesystem path, like /path/to/file/filename.ext, as key.

The abstract method ``getFilePath`` is used to get the path for a file or directory object. The abstract method ``mapKeyToId`` maps a path back to an id."