DB/NPCs: Remove equipment from Huldar

Closes #13032
DB/Quests: The Summoning Chamber/A Curse Upon Both Your Clans

Ok first thing I have to say is even though a Curse Upon Both your clans now works with this script, the spawns are not done in correct way due to missing spells which are not in spell_dbc either but are in sniff, Nayd had no luck searching for them either.

Anyway script for 

http://www.wowhead.com/quest=10602 The Summoning Chamber
http://www.wowhead.com/quest=10585 The Summoning Chamber
http://www.wowhead.com/quest=10544 A Curse Upon Both Your Clans

Also spawn missing deathforge summoners from the summoning area,

Closes #4837
Closes #6776