Notebook DAG-Julia-Pkgs.ipynb does not run under Julia v1.0

[simonschoelly]

In newer Julia versions the package ecosystem has changed in structure, so this notebook has to be adjusted to these changes.

[juliohm]

Thanks @simonschoelly for reporting it. This one requires more work to update. If you are familiar with the new package ecosystem structure, please feel free to submit a PR.