added permission (jump.DoubleJump), added /djump to toggle DoubleJump. (May collide with fly on survival plugin / If it keeps colliding, rollback to v0.0.2)4 v0.0.2: https://github.com/aesoppppp/DoubleJump/releases/download/SNAPSHOT-v0.0.2/DoubleJump-0.0.2-SNAPSHOT.jar
