Support for python 3.4's pathlib

```
Python 3.4 introduced pathlib, an OOP approach to file paths. This new part of 
the standard library also introduces a number of methods for manipulating files 
that are not currently handled by pyfakefs.

https://docs.python.org/3/library/pathlib.html#methods
```

Original issue reported on code.google.com by `anthonyr...@gmail.com` on 20 May 2014 at 10:26
