coldstart demo

I reran the coldstart demo and found that the hrnn-coldstart precision@5 has gone up to 0.092 from 0.040. The baseline has also gone up to 0.0076 from 0.0044. I can understand that there is a shuffle on the item-ids, which causes the baseline changes. But I was wondering if it would cause this amount of variance in the trained model, too.

Related, the demo notebook created fake_user. I wonder if that is actually necessary.

Attaching a script with the new results:
[personalize_coldstart_demo.ipynb.zip](https://github.com/aws-samples/amazon-personalize-samples/files/3677123/personalize_coldstart_demo.ipynb.zip)
Thanks.