Add simple Permissions API

Very simplified version of MinecraftForge/MinecraftForge#1220

This version supports the use of Fake Players in tile entities and other things that can interact with the world. I don't think using fake players is a bad idea, the worldObj, X, Y, Z of the Fake Player should give you the location of the TE/Whatever that is doing the action. And if mods use a unique UUID for each type of block (All Buildcraft quarrys have the same ID, All ComputerCraft turtles, etc.), banning certain blocks on servers should be trivial for protection mods.

Open to conversation.

CC: @luacs1998 @AbrarSyed