Jerry Ma

This commit allows the credentials to be read from ~/.aws/credentials or user-specified (via envvar) file if .s3cfg exists but does not have authentication options. The previous behavior is that s3cmd...

### Repro - Apply https://github.com/pytorch/examples/pull/381 on this repo - `cd` to the ImageNet folder - Run `python main.py --arch resnet18 --seed 0 --gpu 0 /path/to/imagenet/` on a multi-GPU machine, once...