Add Pytorch 4.x/1.0 compatibility, Visual Studio solution files

[sytelus]

This PR adds on the top of https://github.com/bearpaw/pytorch-classification/pull/9.

• Add Pytorch 4.1 and 1.0 compatibility (mainly use item() instead of [0] and torch.no_grad()).
• Also added VS solution files for easy debugging for users who might want to use it.

[bearpaw]

Thanks for the PR. I really appreciate your contribution of upgrading the code to Pytorch 0.4 and 1.0.

However, there is part of the contributions that I do not plan to include in this repo:

• results folder
• visual studio support. I would suggest the users who are interested in VS to see your repo.
• Also what is the gradient ratio scheduler? Any references?