Implement Firework.detonate(). Adds BUKKIT-4538

This implements the detonate method from bukkit by setting the fuse
timer to 0. This makes a firework explode using the normal codepath,
but without waiting for the fuse.
Follow vanilla settings behavior. Fixes BUKKIT-5069

A vanilla server does a series of checks for the client black-listing
certain chat types (commands or chat). This change changes a CB
whitelist to the vanilla blacklist behavior.
Reintroduce disconnection flag that was removed in 1.7 update.
Adds the ability to look up players by UUID. Adds BUKKIT-5071

This commit adds the ability to look up a player by their uuid by calling
Server.getPlayer(UUID).  This is necessary for plugins which use 
persistent player data.  Plugins must now store the player's UUID instead
of user name, so they can keep track of user data across username changes,
 which means a method for looking up players by their UUID is necessary
 to compliment the name based lookup.