Dungeon Finder: Remove players from queue when accept to join a group

This fixes players being multiple times in queue

--HG--
branch : trunk

src/server/game/Groups/Group.cpp

@@ -316,6 +316,7 @@ bool Group::AddMember(const uint64 &guid, const char* name)
     Player *player = sObjectMgr.GetPlayer(guid);
     if (player)
     {
+        sLFGMgr.Leave(player);
         if (!IsLeader(player->GetGUID()) && !isBGGroup())
         {
             // reset the new member's instances, unless he is currently in one of them