Let users use/configure there own Zotero account

[Klap-in]

At the moment only one Zotero (group) account can be configured for the whole wiki.

It would be nice if users can add there own account to the wiki as well, so that not only this global zotero listing should be used.

Difficult in the implementation is that DokuWiki doesn't has a store for keeping info per user.
A way to still implement this is using meta data but, that is not build exactly for this purpose. So (especially) in certain debug cases personal properties can be revealed, which is not desired of course.