[MaNGOS/WotLK] Fix some more UnitMethods

 - InBattlegroundQueue
 - GetBattlegroundTypeId
 - GetBattlegroundId

Signed-off-by: Salja <salja8840@gmail.com>
Merge pull request #39 from Salja2012/master

[MaNGOS/WotLK] Fix some more UnitMethods