GSoC: finagle-smtp - initial

This is initial version of SMTP client for Finagle, which I am working on during GSoC'14.
For now it supports sending independent commands to SMTP server and sending a simple text email to one ore more addresses (without cc, bcc and reply-to). Usage is described in `README.md`. 
So I think by default, finagle will hold open a tcp connection until you actually shut down the client.  From what you said about the length of smtp sessions, it sounds like that's correct behavior, no?  Or is the problem that you are destroying the client and not seeing the request be sent?  We also might have to sequence service(Request.Quit) and service.close(deadline).