Adjusts secondary unarmed attacks

I'm not entirely sure about the extent that biting is used at the moment, but it was still bothering me that humans had a bite attack that was stronger than their punch.

I'm also considering changing the unathi secondary to something other than ```bite/strong```. 15 damage seems extreme, although it might make sense for unathi, I dunno.

Edit: Actually, unathi/taj claws deal a mere 2 points more damage than regular fists. Unless claw damage is buffed, I'm definitely going to remove ```bite/strong``` from unathi, as otherwise the 15 damage is really inconsistent.