Scripts/Quests: Implement quest 12659 (Scalps!)

Thanks Malcrom for condition

Closes #917

sql/scripts/world_scripts_full.sql

@@ -2245,6 +2245,7 @@ INSERT INTO `spell_script_names` (`spell_id`,`ScriptName`) VALUES
 ( 55804, 'spell_q12937_relief_for_the_fallen'),
 ( 54798, 'spell_q12851_going_bearback'),
 (  8593, 'spell_symbol_of_life_dummy'),
+( 52090, 'spell_q12659_ahunaes_knife'),
 -- item
 ( 23074, 'spell_item_arcanite_dragonling'),
 (  8063, 'spell_item_deviate_fish'),