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`. 
not sure this is in the right location.  I don't know SMTP that well, is there any reason why we wouldn't want to start a connection with this?  maybe it should just be in the dispatcher?