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`. 
According to wireshark:
1. QUIT is sent
2. Server responds
3. Server closes connection
4. Client closes connection

Seems like what should be expected.