Store model from script mode in S3

Hi all,

I followed the script mode example [here](https://github.com/aws/amazon-sagemaker-examples/blob/c391082711d4297d157e3a546be29ef422a5974b/sagemaker-script-mode/sagemaker-script-mode.ipynb
) , specificaly [this](https://github.com/aws/amazon-sagemaker-examples/blob/c391082711d4297d157e3a546be29ef422a5974b/sagemaker-script-mode/xgboost_script/train_deploy_xgboost_with_dependencies.py). The model fitted model is fitted like this:

```
model_location = args.model_dir + "/xgboost-model"
pickle.dump(model, open(model_location, "wb"))
```
so I think it is safed in the Docker container. How can I also perist it in S3 (like model.tar.gz what usually happens)? Maybe I can add some lines of code to push to S3 or is there an easier way? Thanks.

Start by reading the referenced sagemaker-script-mode/sagemaker-script-mode.ipynb example and sagemaker-script-mode/xgboost_script/train_deploy_xgboost_with_dependencies.py script. Determine how the fitted model should be persisted in S3 within this example; done means the example clearly demonstrates that persistence and remains usable for deployment.

Written by the indexing model from the issue text.