Various PyTorch 0.4.0 updates

Removed the unnecessary softplus in _address_memory

Made the outer products in NTMMemory.write parallel batch-wise

Corrected the width of the circular convolution adjustment

fixes #2: softmax on the wrong dimension :/

fix typo

fixes #1: pytorch 0.3 adjustments

cleanups

add .gitignore

cleanups

train: move train_batch() and evaluate() from tasks to train.py

ntm: fix batching, clone() vector key so it can be reshaped

README: increase visualization size (fixup)

README: show new plots for the repeat-copy task

tasks: add repeat-copy task