Fix links and other issues.

Update download_datasets.sh

Update README for ImageNet model weights and configs

Update download script for new model URLs

Update SRResNet_x4-SRGAN_ImageNet.yaml

Update SRGAN_x4-SRGAN_ImageNet.yaml

Merge pull request #90 from AlexHorduz/patch-1

Update test.py

Update train_gan.py

Upgrade

Upgrade

Add some config file

Optimize the model training mode and add the pre-training model

Add some config file

Add some config file