Runtime requirement behavior and Blackfire for PHP update

Change effective on 23 November 2016

For forward compatibility with future functionality, PHP Applications on Heroku must now declare a PHP runtime version requirement in the require section of composer.json or list a dependency that contains such a requirement if the require-dev section contains a PHP runtime version requirement or lists a dependency that contains such a requirement.

The blackfire extension has been updated to version 1.14.1.