v0.2 Release: FP16, Distributed, and Usability updates

Our main goal with this release is two-fold:

• address concerns around usability
• Update repo with new code for FP16, distributed training

Usability

• We've brought our training/generation code more in line with the pytorch word language model example
• Provide PyTorch classifier module/function for classifying sentiment from input text tensor
  • Provide pretrained classifiers/language models for this module
  • Provide simple standalone classifier script/example capable of classifying an input csv/json and writing results to other csv/jsons
• Flattening our directory structure to make code easier to find
• Putting reusable PyTorch functionality (new RNN api, weight norm functionality, eventually all fp16 functionality) in its own standalone python module to be published at a later date

FP16 + Distributed

• FP16 optimizer wrapper for optimizating FP16 models according to our [best practices] (https://github.com/NVIDIA/sentiment-discovery/blob/master/analysis/reproduction.md#fp16-training)
  • available in fp16/fp16.py
• Lightweight distributed wrapper for all reducing gradients across multiple gpus with either nccl or gloo backends
  • model/distributed.py
• distributed worker launch script
  • multiproc.py