A PyTorch reproduction of koncept512 code

Hi! Your work is interesting.

I just reproduce your Keras code for koncept512 model using PyTorch.
The new results (SRCC: 0.912 | PLCC: 0.927) are very close to what you have got (SRCC: 0.919 | PLCC: 0.932) in koncept512_train_test_py3.ipynb.

If you want, feel free to post the following code link into your official repository :-)
https://github.com/ZhengyuZhao/koniq-PyTorch

