Turn revisions off in plugin instead of config.php?

1. Create a no-revs.php
2. Set the contents to <?php defined('WP_POST_REVISIONS') or define ('WP_POST_REVISIONS', false);
3. Place it in the Must Use Plugins Folder located at wp-content/mu-plugins.

Be warned; It is recommended that you to have at least 3 post revisions to avoid any loss of data.