[Battleground] Join with opposite faction

[Warbike]

Hello, since we already use premade group to play with enemy faction's member to make Dungeon/Raid groups, BG teams are build using cross-faction mode, Horde can whisp Alliance's players and the other way around.
It would be great to make possible to join BG with members of the opposite faction since we can do everything with them except Battleground(i didn't test if it's possible for Arena).


Thanks for making Freakz great everyday!