Add mlflow tracking

[andodet]

First of all thanks for the project, it's an interesting way to take a stab at reducing the amount of boilerplate needed even for fairly simple models. Secondly, it would be interesting to implement experiment/run tracking using MLflow.

Have a working example on the Image classification_PyTorch/ template, happy to submit a PR if you consider this of any interest.

[jrieke]

Yeah this would be great, feel free to open a PR, then I'll have a look!