OpenPifPaf port for RunwayML

Link to OpenPifPaf code: OpenPifPaf

@article{kreiss2019pifpaf,
  title={PifPaf: Composite Fields for Human Pose Estimation},
  author={Kreiss, Sven and Bertoni, Lorenzo and Alahi, Alexandre},
  journal={CVPR, arXiv preprint arXiv:1903.06593},
  year={2019}
}