Adjust attribution for wikimedia images

[acka47]

Re. #321 (comment). Instead of using imageinfo.Artist.value we should use imageinfo.Attribution.value for the creator attribution.

[acka47]

The reason: users can basically put anything into the "creator" field in Wikimedia Commons. Showing all the content of the field in lobid-organisations isn't necessary. Here is a quite extreme case that dosn't look good at all:

[acka47]

I just noticed that this won't work for the example shown as you don't get back the Attribution information via the API, see https://commons.wikimedia.org/w/api.php?action=query&format=json&prop=imageinfo&list=&titles=file%3AMuenster_Dioezesanbibliothek_4634.jpg+&iiprop=extmetadata. https://lizenzhinweisgenerator.de/ gives back a very long attribution text for this image.

I am not sure whether it would make sense to prefer the Attribution object if available over the Artist object. Leaving this open for now.

[acka47]

Closing.