Microsoft Outlook headers not being detected in replies

Although https://github.com/github/email_reply_parser/pull/54 seems to fix one type of Outlook email reply, one with a quoted body, I don't believe that the following example reply from an Outlook mail client is currently working:

```
Outlook email reply with a team mention in the email body.

From: CRM Comments [crm-comment@example.com]
Sent: Friday, 23 March 2012 5:08 p.m.
To: John S. Greene
Cc: Jane Q. Codes
Subject: Re: [@organization/team] Discussion about mail replies. (#1)

Should the team mention from the subject line be parsed in the comment?

> Here is quoted text.
>
```

I've pushed up a test via https://github.com/github/email_reply_parser/commit/33ccba0a4b15a60db42bdbec56a9d6cb783ed6db that fails locally on the example fixture (pushed in https://github.com/github/email_reply_parser/commit/51639404b4e14eeba934d11bd77837136efdeab9).

In the example here, I believe only the following string should be returned:

```
Outlook email reply with a team mention in the email body.
```

Start with the example fixture and the failing test from commits 33ccba0a4b15a60db42bdbec56a9d6cb783ed6db and 51639404b4e14eeba934d11bd77837136efdeab9. Reproduce the Outlook reply case and adjust parsing so only the unquoted body text is returned, then verify the fixture passes.

索引モデルが issue の本文から書いたものです。