Added status code to app/check.php
merged branch maxromanovsky/app-config-status-code (PR #516)

This PR was squashed before being merged into the master branch (closes #516).

Discussion
----------

Added status code to app/check.php

This change could be useful in build scripts. `app/check.php` could be executed in order to check that build environment is sane.
Changes:
1. Added status code to `app/check.php`
1. Updated `README.md`

Commits
-------

ded4360 Added status code to app/check.php
tweaked previous merge