Moved battleground achievement scripted checks into scripts

Call ACHIEVEMENT_CRITERIA_TYPE_SPECIAL_PVP_KILL updates in code
Implemented achievements: Save the Day, Quick Cap, Warsong Expedience

--HG--
branch : trunk

src/server/game/Entities/Unit/Unit.cpp

@@ -715,7 +715,12 @@ uint32 Unit::DealDamage(Unit *pVictim, uint32 damage, CleanDamage const* cleanDa
         DEBUG_LOG("DealDamage: victim just died");
 
         if (pVictim->GetTypeId() == TYPEID_PLAYER)
+        {
             pVictim->ToPlayer()->UpdateAchievementCriteria(ACHIEVEMENT_CRITERIA_TYPE_TOTAL_DAMAGE_RECEIVED, health);
+            // call before auras are removed
+            if (Player* killer = ToPlayer())
+                killer->GetAchievementMgr().UpdateAchievementCriteria(ACHIEVEMENT_CRITERIA_TYPE_SPECIAL_PVP_KILL, 0, 0, pVictim);
+        }
 
         Kill(pVictim, durabilityLoss);