Add support for live-Artifacts

[Qwlouse]

Added artifacts cannot be updated anymore. It would be nice to have a way of adding an Artifact that is then watched and updated in the database whenever it is changed.

[kirk86]

That's especially handy when you have plots you wanna generate and update only after some criteria, for instance a drop in validation loss. I spend almost a day going back and fort the docs in hope of finding sth like this.