zombie_source.mdl fixed

I present my zombie_source.mdl cool edit. No more "no headshot" zombie skin in your ZM servers with custom hitboxes.

The original author is wanted, so I can add him in the authors list !

You MAY use it ONLY, if your server is free of charge or it's not for sale for money, or any other method of getting a goods/money with my skin involved !

Pros :

-head bone and head hitbox

-working mouth

-better hand holding

-rotated head

-perfect head hitbox

-standard skeleton and hitboxes

-can be used as ZM or regular skin

-everything else is untouched

Cons :

-wrong place of neck hitbox