Set subject of new newsletters to "Draft newsletter"

assets/js/src/newsletters/types.jsx

@@ -26,6 +26,7 @@ define(
           action: 'create',
           data: {
             type: type,
+            subject: 'Draft newsletter',
           }
         }).done(function(response) {
           if(response.id !== undefined) {

lib/Router/Newsletters.php

@@ -250,6 +250,7 @@ class Newsletters {
   function create($data = array()) {
     $newsletter = Newsletter::create();
     $newsletter->type = $data['type'];
+    $newsletter->subject = $data['subject'];
     $newsletter->body = '{}';
 
     // try to load template data