add model arguments to densepose apply_net.py (#650)
add model arguments to densepose apply_net.py (#650)

Summary:
Added the ability to provide additional model arguments to densepose's `apply_net.py`, principally in order to be able to run it on CPU. Small copy-paste from `demo/demo.py`
Pull Request resolved: https://github.com/facebookresearch/detectron2/pull/650

Differential Revision: D19323992

Pulled By: ppwwyyxx

fbshipit-source-id: c193ceb31b40a73cc8329114117c61e5067f50f3

facebookresearch/detectron2,facebookresearch/detectron2,facebookresearch/detectron2