…ve LF line endings and all files stay unix on commit

Add note about setting PYTHONIOENCODING=UTF-8 env var for running
examples

Example will `tee` stdout to `/tmp/samples` from conditional and
unconditional generation scripts.

add description for flags

added python download script and modified requirements to add the modules needed. Tested in Windows Version 10.0.17134 Build 17134  and Ubuntu 18.04.1 LTS

This write-up was loosely inspired in part by Mitchell et al.’s work on
[Model Cards for Model Reporting](https://arxiv.org/abs/1810.03993).
Adding such model usage sections could be good practice in general for
open source research projects with potentially broad applications.

This enables multi-GPU or distributed training using Horovod

…w training the 345M model.

Add toposort to requirements

…acting to typos.

…ional_samples.py.

Added the medium blog link "Beginner’s Guide to Retrain GPT-2 (117M) to Generate Custom Text Content"

Updated README.md

…utf-8.

tensorflow 1.12.0 leads to error "no attribute sort". Fix is to upgrade to tensorflow 1.15.0 (openai#242)