Scripts/Instance: The Vortex Pinnacle

More to come... Creature spawns and Grand Vizier Ertan for now.
- [ ] Slipstream
- [x] [**Grand Vizier Ertan**](http://www.wowhead.com/npc=43878)
 - [ ] Lurking Tempest
- [x] [**Altairus**](http://www.wowhead.com/npc=43873)
- [ ] [**Asaad**](http://www.wowhead.com/npc=43875)

Please add some comments to this function, it is not immediately clear what it's supposed to do