general.php

<?php

/**
 * General Configuration
 *
 * All of your system's general configuration settings go in here.
 * You can see a list of the default settings in craft/app/etc/config/defaults/general.php
 */
define('SERVER_NAME', $_SERVER['SERVER_NAME']);
if (!isset($_SERVER['HTTPS']) || $_SERVER['HTTPS'] != "on") {
    define('SITE_URL', "http://".SERVER_NAME . '/');
} else {
    define('SITE_URL', "https://".SERVER_NAME . '/');
}

return array(
    '*' => array(
        'devMode' => false,
        'allowedFileExtensions' => 'jpeg, jpg, pdf, png, gif',
        'allowUppercaseInSlug'  => false,
        'defaultImageQuality'   => 75,
        'filenameWordSeparator' => '-',
        'maxUploadFileSize'     => 5000000,
        'omitScriptNameInUrls'  => true,
        'useEmailAsUsername'    => true,
        'errorTemplatePrefix' => '_views/errors/',
        'featureEnabled' => [
            'faves' => false
        ],
        'siteUrl' => SITE_URL,
    ),
    ,
    'staging-url.co.uk' => array(
        'devMode' => true
    ),
    'live-url.co.uk' => array(
        'devMode' => false
    )
)