possibility to specify sender address for froxlor as the admin-email address, custom or empty for system-default; fixes #1217

Signed-off-by: Michael Kaufmann <d00p@froxlor.org>

lng/en.lng.php

@@ -2389,6 +2389,8 @@ Yours sincerely, your administrator',
 			'top' => 'Admin user',
 			'title' => 'Let\'s create the main administrator user.',
 			'description' => 'This user will be granted all privileges to adjust settings and add/update/delete resources like customers, domains, etc.',
+			'use_admin_email_as_sender' => 'Use the email address above as sender address. If unchecked, please specify a sender address below.',
+			'use_autogenerated_email_as_sender' => 'Leave empty for default: admin@servername',
 		],
 		'system' => [
 			'top' => 'System setup',