text: Title: Save generator and load it only for prediction
  Body: Hello,
  
  Thank you for your implementation of cycle gans, it is very clear. I would like to ask if there is a way to save the generators every 500 iterations (exactly when they predict the test images) so I can load them in a different moment and only perform prediction in a specific test set with the loaded model (in a new code, independent of cycle_gan.py)
  
  Thank you,
  Agelos