Adds a lives system, with a few commands:
/setreward- sets the reward for if a bounty player survives. sets it to whatever item is in your main hand
/bounty- picks a player to be the hunted one.
/bountyend- ends the bounty early and gives the hunted player their reward for surviving
the bounty will automatically end if a player kills the hunted player, and whoever kills them gains a life, while the hunted player loses an extra life
