Add support to python Path-like objects

[diraol]

In order to better support python 3.6, it would be nice to support Path-like objects instead of only strings on the "path" arguments/attributes.

https://docs.python.org/3/library/pathlib.html

[asottile]

We welcome pull requests if you'd like to take a first stab at this :)

[diraol]

I'll try to work on it, but probably only on next week ;)

[dahlia]

We might be possible to utilize os.fspath() (introduced by PEP 519).