DB/SAI: Alpha Worg

Original Script by @Malcrom, updated by me

Garwal should be invisible to players without aura from http://www.wowhead.com/spell=43060 this is also the spell which forces reputation on garwal to be hostile but the server side spell which Garwal is meant to cast 43062 Alpha Worg: Garwal's Invisibility which is in spell dbc now but does not work so players can still see him without quest but hes friendly.

Closes #8412