Add a Server emitter that handles fetching a server engine and performing a Lua emission of an event.

[bbuck]

Emitting server events should only use one emitter and not have to know about engines and what-have-you. Something like:

server.Emitter.Emit("init", nil)

[bbuck]

Going to go ahead and rope in moving the server engine mutator/pool creation into the same package that the emitter gets placed into.