DB/Condition: Add condition to sunwell-blade spell to target only Dar'Khan Drathir

Closes #16122

sql/updates/world/2015_12_29_02_world.sql

@@ -0,0 +1,4 @@
+-- 
+DELETE FROM `conditions` WHERE `SourceTypeOrReferenceId`=17 AND `SourceGroup`=0 AND `SourceEntry`=28516;
+INSERT INTO `conditions` (`SourceTypeOrReferenceId`,`SourceGroup`,`SourceEntry`,`SourceId`,`ElseGroup`,`ConditionTypeOrReference`,`ConditionTarget`,`ConditionValue1`,`ConditionValue2`,`ConditionValue3`,`NegativeCondition`,`ErrorType`,`ErrorTextId`,`ScriptName`,`Comment`) VALUES
+(17,0,28516,0,0,31,1,3,16329,0,0,0,0,'',"Only Dar'Khan Drathir can be a target for Sunwell Torrent");