Added blacklisting ability

New config section

# These are mobs that will not count towards users shards.
# You can find the different mob types here: https://hub.spigotmc.org/javadocs/spigot/org/bukkit/entity/EntityType.html
# If you wish to not send a message to the player when killing said mob
# (if they have an empty shard) then set the 'message.enabled' to false.
blacklist:
  message:
    enabled: true
  mobs:
    - 'ender_dragon'
    - 'wither'