Improved the /cor reload command

Using /cor reload now updates all existing bosses with the new data and
removes bosses that no longer exist in the config(e.g. after renaming
them)
Made the CommandAbility use the boss as CommandSender, so the /tell
command, for instance, will now be coming from the boss itself.
The command ability will now parse {PLAYER} to enable commands directed
at a player.
TODO: Fix the EnchantFireTick immunity