Support for Microsoft custom ARF format

[jleroy]

Hi,

This pull request add support for Microsoft (Hotmail, MSN, Live, Outlook) ARF implementation, which is different from the "real" ARF format (RFC 6650).
The X-HmXmrOriginalRecipient, X-Reporter-IP and X-Message-Guid headers are added to the message reported as spam, and send as an RFC 822 attachment.

Sample output:

{
  "action": "failed",
  "addresser": "sender@example.com",
  "alias": "",
  "deliverystatus": "",
  "destination": "hotmail.com",
  "diagnosticcode": "This is a Microsoft email abuse report for an email message received from IP 123.123.123.123 on Tue, 21 Apr 2015 09:22:13 -0700",
  "diagnostictype": "SMTP",
  "feedbacktype": "abuse",
  "lhost": "10.182.89.225",
  "listid": "",
  "messageid": "d4cb0d6593464552a34f4429b3e7f92f@example.com",
  "reason": "feedback",
  "recipient": "recipient@hotmail.com",
  "rhost": "123.123.123.123",
  "senderdomain": "example.com",
  "smtpagent": "Microsoft Junk Mail Reporting Program",
  "smtpcommand": "",
  "subject": "Example message",
  "timestamp": 1429633333,
  "timezoneoffset": "-0700",
  "token": "d86ca075c5c1b81d97bd0a56b5fdb58a1a182993"
}

[coveralls]

Coverage increased (+0.22%) to 95.6% when pulling 38df108 on jleroy:MicrosoftARF into d6be0fc on azumakuniyuki:master.

[coveralls]

Coverage increased (+0.22%) to 95.6% when pulling 38df108 on jleroy:MicrosoftARF into d6be0fc on azumakuniyuki:master.

[azumakuniyuki]

Hi,
Thanks for the great patches !!