Add support for fake players from mods. Closes #175, #176, related #25.

Mods implementing their own fake player will now send events with
a corresponding Bukkit fake player. The fake player name will be
logged when first initialized, for example:

    [INFO] [FakePlayer] Initializing fake player: [RedPower]

You can then op this fake player or assign permissions appropriately.

The fake player name will be determined as follows:

* If the mod provides a name, it will be used
* If the mod does not provide a name, its class name will be used
* If a custom name is assigned, it will be used in all cases

The name can be overriden in bukkit.yml mcpc.fake-players, specifying
the mod fake player class name and the preferred username.

Thanks to Maeyanie for the original FakePlayer implementation from
https://raw.github.com/Maeyanie/BuildCraft/master/buildcraft/core/FakePlayer.java