Model with ' ' in `model_path` fails ACI deployment

To reproduce:
1. rename `tutorials/image-classification-mnist-data/sklearn_mnist_model.pkl` to `sklearn mnist model.pkl`
2. edit `tutorials/image-classification-mnist-data/img-classification-part2-deploy.ipynb` to reflect Step 1 (in model-registration, cell 1, and in `score.py`, cell 3)
3. run `img-classification-part2-deploy.ipynb`- the "Deploy in ACI" step fails:

```
Service deployment polling reached non-successful terminal state, current service state: Transitioning
Operation ID: b8141a0c-55e4-4cd4-b30d-da7d1debd3e1
More information can be found using '.get_logs()'
Error:
{
"code": "DeploymentTimedOut",
"statusCode": 504,
"message": "The deployment operation polling has TimedOut. The service creation is taking longer than our normal time. We are still trying to achieve the desired state for the web service. Please check the webservice state for the current webservice health. You can run print(service.state) from the python SDK to retrieve the current state of the webservice.
Please refer to https://aka.ms/debugimage#dockerlog for more information."
}
```

The ACI deployment also failed when `model_path` specifies a folder with spaces in its name. This did _not_ appear to affect `LocalWebservice` or AKS deployments.

Reproduziere den Fehler, indem du tutorials/image-classification-mnist-data/img-classification-part2-deploy.ipynb befolgst, einschließlich des umbenannten Modellpfads in der Modellregistrierungszelle 1 und der score.py-Zelle 3. Vergleiche das ACI-Bereitstellungsverhalten mit dem gemeldeten Verhalten von LocalWebservice und AKS. Erledigt ist die Aufgabe, wenn die ACI-Bereitstellung erfolgreich ist, sobald der Pfad zur Modelldatei oder zum Modellordner Leerzeichen enthält.

Vom Indexierungsmodell aus dem Issue-Text verfasst.