Karma: Added command to list top5 karmas.

Signed-off-by: Jakub Novak <jakub.novak@gmail.com>
So karmees is now a sorted list. Thus, I believe you do not really need that `c = 1` and then `c += 1` but you can rather do something like
```python
for position in range(1, 6):
    (nick, karma) = karmees[position]
    top5 += "{0}. {1} with {2}\n".format(position, nick, karma)
```