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`. 
The way this works has changed slightly--right now, `StackClient` is the new way of doing this.  I know you're near the end of your summer, so you might not have time to change this, but might be worth looking and seeing if switching over is simple.