LPS-44438 improve user-display taglib

Hey Nate,

We have been working on the staging UI and part of that, we have been improving the user-display tag (this is an old one) to have a style where we can show a user image on the staging UIs.

@LeventeHudak and @DanielKocsis were working on the taglib changes @jbalsas reviewed the CSS stuff, I was going trough the JSP/taglib code, so this is really a team effort :)

Can you please review the CSS and then push to Brian to check the rest?

Thanks,

Máté