Only show duel stats if the user has dueled before
Only show duel stats if the user has dueled before

duel_stats used to be None if the user hadn't dueled before, now we check duels_total instead

Fixes #523

pajlada/pajbot,pajlada/pajbot,pajlada/pajbot,pajlada/tyggbot,pajlada/tyggbot,pajlada/pajbot,pajlada/tyggbot,pajlada/tyggbot