Karma: Added command to list top5 karmas.

Signed-off-by: Jakub Novak <jakub.novak@gmail.com>
Well, this will send multiple lines out there. The only problem I have with this is that it creates five lines of output. That might be OK in general but it might create a bit too much pollution in the channel/room. However, I think I'm pretty OK with it for now.