Update to 5.2.27

Changelog: https://github.com/PHPMailer/PHPMailer/releases/tag/v5.2.27

PR: 233420
Reported by: Derek Schrock <dereks@lifeofadishwasher.com>
MFH: 2018Q4
Security: b036faba-edd8-11e8-b3b7-00e04c1ea73d
Sponsored by: Netzkommune GmbH