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`. 
Is there a reason these MySQL tests are rearranged here? Could you undo (and move to a separate pull request if intentional) to keep this focused on the SMTP work? Thanks!