Show model source when available as the fully qualified class name

[gidili]

From @rgerkin: When I click the name of a model on the Test Scores page, for "Class Source" it shows "None" with a link to a URL with "None" in it that doesn't go anywhere. Shouldn't it know the source and be able to link to it? Actually, I'm not sure we have a well-defined way of actually linking to the correct version of the source, but it should at least know the full name of the class from when it was registered (e.g. neuronunit.models.reduced.ReducedModel).

[gidili]

This used to be the URL field, so it's not showing the fully qualified class name because the URL is empty and it has nothing to show.

• It should show the url if any is there, followed by the fully qualified class name (not a link for now, it could be but it takes some logic and decision making to decide which neuronunit branch it should come from) if available (this is available only for preset classes or classes uploaded with this field populated if everything went well)
• It should show None without it being a link if none of the above is available

[rgerkin]

That sounds reasonable.