RFC 7239 compliant preamble script for Phabricator

Summary:
Fix headers to allow two things:

• correct detection of http/https
• remote address is use instead of Docker engine address

Reference:

• https://tools.ietf.org/html/rfc7239
• https://secure.phabricator.com/book/phabricator/article/configuring_preamble/

Fixes T915.

Test Plan: Tested on https://devcentral.nasqueron.org/

Reviewers: Sandlayth

Subscribers: Nasqueron Docker deployment squad

Tags: Docker images

Maniphest Tasks: T915

Differential Revision: https://devcentral.nasqueron.org/D484