Default mailgun to "disabled"

Could otherwise cause confusion with users who have SMTP enabled

modsForHesk_settings.inc.php

@@ -29,6 +29,6 @@ $modsForHesk_settings['customer_email_verification_required'] = 0;
 $modsForHesk_settings['html_emails'] = 1;
 
 //-- Mailgun Settings
-$modsForHesk_settings['use_mailgun'] = 1;
+$modsForHesk_settings['use_mailgun'] = 0;
 $modsForHesk_settings['mailgun_api_key'] = 'KEY';
 $modsForHesk_settings['mailgun_domain'] = 'DOMAIN';