Add 'envelopeFrom' and 'envelopeTo' fields to parsedEmail

There is currently no way to know what the "envelope" to and from addresses were for an email.  For example, if you send an email to **address1@mydomain.com** which then redirects that message to **address2@mydomain.com**, the `from` field will be **address1@mydomain.com** and **address2@mydomain.com** will show up nowhere in the parsed email data.

This pull request just stores the `connection.from` and `connection.to` properties, and then adds them to the `parsedEmail` before passing it along to the event listeners/webhook.