Fix KeyError in chk_win

This fixes the error below with wolf cub that has been appearing for a while now, and also prevents similar errors from happening with monster and traitor in the same function.

```
Exception in thread Thread-1126:
Traceback (most recent call last):
  File "/usr/lib/python3.2/threading.py", line 740, in _bootstrap_inner
    self.run()
  File "/usr/lib/python3.2/threading.py", line 693, in run
    self._target(*self._args, **self._kwargs)
  File "/home/lykos/lykos/modules/wolfgame.py", line 1746, in reaper
    chk_win(cli)
  File "/home/lykos/lykos/modules/wolfgame.py", line 1296, in chk_win
    lrealwolves = len(var.list_players(var.WOLF_ROLES)) - len(var.ROLES["wolf cub"])
KeyError: 'wolf cub'
```

I haven't been able to test this because I'm not sure what exactly triggers it. If someone could test it, I'd appreciate it.