R1:5ba6e241c453

Check required PHP version

Summary: D1999#4

Test Plan:
/ with HPHP.
/ with required version bumped to 5.14.0.

Reviewers: epriestley

Reviewed By: epriestley

CC: nh, aran, epriestley

Differential Revision: https://secure.phabricator.com/D2020