Allow MetaMTAMail to send with a raw "From" address
- For the import tools, I want to send from "Phacility Support <email@example.com>".
- In the general case, I want to send billing mail from merchants (T7607) later on.
Test Plan: Sent an email and saw the desired "From" address.
Reviewed By: btrahan
Differential Revision: https://secure.phabricator.com/D12100