Add joinable boolean check to team.BestAutoJoinTeam

Added check to see if the team is joinable when using team.BestAutoJoinTeam(). team.SetUp includes the boolean isJoinable as the 4th argument, defaults to true. Useful to have a check for if it is false
Merge pull request #512 from rtlk/master

Add joinable boolean check to team.BestAutoJoinTeam