Upgrade to PHP 5.6.27
Summary: Resolves T1032
Test Plan: Rebuild the image's tags on Dwellers, `php -i```
Reviewers: Sandlayth, dereckson
Subscribers: Nasqueron Docker deployment squad
Tags: Docker images
Maniphest Tasks: T1032
Differential Revision: https://devcentral.nasqueron.org/D688