released wheels do not specify dependencies

[FelixSchwarz]

The released wheels do not specify any dependencies even though the code relies on modules outside the standard library.

For example image_net_data_loader.py requires torch and torchvision.

Also there are dependencies for progressbar, requests and gdown in common/downloader.py.

Could you add these dependencies to the wheel? However please do not fix any specific version unless you really have to (and if you need, default to >= X.Y instead of going for == X.Y.Z).

If you have model-specific dependencies (e.g. just for resnet) or version restrictions, please use Python extras.

[quic-mangal]

@quic-hanwxion, could you please take a look at this? Thanks.