Show username of users when sharing

[diocas]

When I want to share something with a user, I can search for him but the list only contains the display names.
In large institutions we might have multiple users with the same name, therefore we need a way to distinguish them. It would be great to see the usernames (or, in some cases, emails) in this list, since the user pictures might not even be available.

This information is already being sent in the reply from the API.