Pytorch GPU install instructions

At the end of these instructions you will have:

1. A fully working conda environment running pytorch on GPUs

# create conda env
conda create -n torch python=3.6

# activate the created environment
conda activate torch

# install numpy
pip install numpy

# install torch (cuda 9)
conda install pytorch torchvision cuda90 -c pytorch

# if cuda 9 fails, install this way using cuda 8 
conda install pytorch torchvision -c pytorch
conda install cuda80 -c soumith

# test gpu install
python -c 'import torch; print(torch.rand(2,3).cuda())'