Modify: change dataset download url

[DrawingProcess]

Open Issue: #202

data/download_cyclegan_dataset.sh

• from: https://people.eecs.berkeley.edu/~taesung_park/CycleGAN/datasets/
• to: https://efrosgans.eecs.berkeley.edu/cyclegan/datasets/

data/download_pix2pix_dataset.sh

• from: https://people.eecs.berkeley.edu/~tinghuiz/projects/pix2pix/datasets/
• to: https://efrosgans.eecs.berkeley.edu/pix2pix/datasets/