pip version is corrupted

[muzhig]

pip install openapi-core==0.5.0
installed package contains different structure than this repo on github:

schema
validation
wrappers
__init__.py
components.py
enums.py
exceptions.py
infos.py
media_types.py
models.py
operations.py
parameters.py
paths.py
request_bodies.py
responses.py
schemas.py
servers.py
shortcuts.py
specs.py
validators.py
wrappers.py

Which obviously isn't functioning correctly: for example it has two different modules with same exception classes, which leads to undefined behavior.

When installed from github, the package seems correct.
(Python 3.6, MacOS)

[muzhig]

Also seems like README isn't correct as well

[pbasista]

This seems like a duplicate of #47. As of outdated README, I think it should be tracked in a separate issue.