This commit introduce the python-binding for iteracting with
CRI runtime via GRPC.
The client code is generated by protocol buffer [1] by using api.proto
in kubernetes/cri-api repo.
The generated CRI client code couldn't pass the pep8 check so this
commit also configure flake8 to skip the zun/criapi directory.
[1] https://developers.google.com/protocol-buffers/docs/pythontutorial
Implements: blueprint add-support-cri-runtime
Change-Id: I2e1a20b47fec5af1f4977148431e1135abd49812
7c7ee59026