Enhancement: Add owner and resharer in collaborators list

The top of the collaborators list now display new entries for the resource owner and the resharer when applicable,
and also visible when viewing a child resource of a shared folder (indirect share).

https://github.com/owncloud/web/issues/2898
https://github.com/owncloud/web/pull/2915
https://github.com/owncloud/web/pull/2918
