ModuleNotFoundError: No module named 'eval_util'

Following the steps in README for running locally, I'm running into an error:

```
$ ls
youtube-8m
$ gcloud ai-platform local train \
> --package-path=youtube-8m --module-name=youtube-8m.train -- \
> --train_data_pattern='gs://youtube8m-ml/2/frame/train/train*.tfrecord' \
> --train_dir=/tmp/yt8m_train --frame_features --model=FrameLevelLogisticModel \
> --feature_names='rgb,audio' --feature_sizes='1024,128' --start_new_model
Traceback (most recent call last):
File "/Users/gorkem/anaconda3/lib/python3.6/runpy.py", line 193, in _run_module_as_main
"__main__", mod_spec)
File "/Users/gorkem/anaconda3/lib/python3.6/runpy.py", line 85, in _run_code
exec(code, run_globals)
File "/Users/gorkem/kaggle/yt8m/code/youtube-8m/train.py", line 20, in
import eval_util
ModuleNotFoundError: No module named 'eval_util'
```
Later, adding the directory `youtube-8m` to PYTHONPATH solves the problem for me, but that probably isn't the intended usage.

Start with the README's local training command and youtube-8m/train.py, especially its import of eval_util. Check how --package-path and --module-name affect module resolution, then run the documented command without manually setting PYTHONPATH. Done means the command no longer raises ModuleNotFoundError for eval_util.

Written by the indexing model from the issue text.