Fix BioMed for 1.4.6

As it seems, the Bukkit team has introduced a safeguard feature to CraftBukkit, which forces the plugin developer to update for every version of Minecraft.
You can read more about it here: http://forums.bukkit.org/threads/safeguarding-against-unchecked-and-potentially-damaging-plugins.116749/

What this "safeguard" basically does is it hides all packages in net.minecraft.server.<minecraftversion>.<package> and org.bukkit.craftbukkit.<minecraftversion>.<package>. This should try to prevent that an old plugin is able to harm a server, as far as I can tell.

I just updated CraftBukkit to the newest version and fixed the imports, so BioMed will work on 1.4.6 servers.
(It won't work with any other minecraft version though :/)