Add missing files
Add Logging and refactor types

-1- implements logging system (use hslogger)
-2- refactor Types
Implements few functions to simplify sending emails
Implement the process to forward the emails
Forward message to recipients:

- fixe flushing
- add some debug/notification messages
- fix the SMTPConnection structure: use methods and do not forget to
  flush the bytestring.
Minor update: move SMTPConnection in a different file
ESMTP and improvments

SMTP/Parser: update the parser to manager extention parameters
Use a data structure to describe a Connection (an abstaction from
handler) (also fix the issue when sending the command by flushing the
Handle).
SMTPConnection: default tool to manage a handle

- generate a random number to associate with a connection
- when generating a unique file name (for the mail data),
  append this connection ID to this file name
- use SMTPConnection for server part too
- improve logging system: when debug mode activated, show all the read
  and written data.
Version 0.0.1.x:

* manage users:
  * user info
  * identification
  * multiple mailbox
* manage domain:
  * multiple domain
* Server:
  * receive RFC5321 commands (SMTP)
  * implement AUTH PLAIN method (ESMTP) (do not use authentication yet
    since TLS/SSL is not implemented yes
* Client:
  * send RFC5321 commands (SMTP)
  * send email to multiple domains
  * detect Mx Domains
  * send one email for recipients in the same domain