Altered build timestamp format to use RFC 3339
Altered build timestamp format to use RFC 3339

Summary: Build timestamps now include timezone information and conform to [RFC 3339](https://tools.ietf.org/html/rfc3339)

Test Plan: - [Internal build](http://jenkinsmaster.mediamiser.internal:8080/view/Mercury%20libraries/job/mercury-avogadro-chris/22/)

Reviewers: samer.albuhaisi

Reviewed By: samer.albuhaisi

Differential Revision: http://phabricator.mediamiser.internal/D2765

MediaMiser/avogadro