Feature/docker

[motokimura]

Hi @garrickbrazil, thank you for making the code public.

I added Dockerfile to this repo.
I hope this helps someone who cannot prepare old CUDA environment in local.

For usage, please see docker/README.md.

[motokimura]

Note:

• I've checked the pre-trained models provided by garrickbrazil could reproduce mAP with this docker environment.
• I've not tested the models trained with the docker could reproduce the results.

Reports from someone tried training are more than welcome.
I used the same versions for pytorch, torchvision, and other libraries (see docker/requirements.txt) so I hope it reproduces training as well.