Disable UI-driven updates in staging and production

This PR follows the initial merge (5f84a32) and revert (627b63d) of commit 0751c5a.

See this PR for the initial discussion: #125

I took the liberty of adding a single new line at the end of `staging.php` and `production.php` (it's actually the default behavior in my Sublime Text config), as it seemed to already be the standard in most of the other project files.