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
- [ ] [**Altairus**](http://www.wowhead.com/npc=43873)
- [ ] [**Asaad**](http://www.wowhead.com/npc=43875)

pretty sure there already is a predicate in core for that