Added missing import

[DavidLandup0]

Looks like an import was missing for download_url_to_file from from torch.hub, in the AI Ephiphany reconstruction section. I've added the import at the top of the file, with other imports, to abide by the formatting already present, though, it might be a better idea to import it just before the new custom ResNet50 since it isn't used anywhere before?

[DavidLandup0]

Additionally turned off Matplotlib axis for cleaner output images - this one is more of a subjective change, so it might actually be against what you originally wrote. Feel free to prune the change if you don't like it :)