Error when adding notebook lifecycle configuration

Hi, Thanks for the great script!

When I tried to add lifecycle configuration on AWS CLI, error below is happened:

```
XXX:~/environment/amazon-sagemaker-codeserver/install-scripts/notebook-instances $ aws sagemaker create-notebook-instance-lifecycle-config \
> --notebook-instance-lifecycle-config-name install-codeserver \
> --on-start Content=$((cat setup-codeserver.sh || echo "")| base64) \
> --on-create Content=$((cat install-codeserver.sh || echo "")| base64)

Error parsing parameter '--on-create': Expected: '=', received: 'EOF' for input:
cyBSZXNlcnZlZC4KIyBTUERYLUxpY2Vuc2UtSWRlbnRpZmllcjogTUlULTAKCiMhL2Jpbi9iYXNo
```

There is `EOF` in the middle of script, so I think quotation is needed when adding lifecycle configuration with AWS command:
```
aws sagemaker create-notebook-instance-lifecycle-config \
--notebook-instance-lifecycle-config-name install-codeserver \
--on-start Content="$((cat setup-codeserver.sh || echo "")| base64)" \
--on-create Content="$((cat install-codeserver.sh || echo "")| base64)"
```

Thanks,