- Implements scheduler worker for welcome and post notifications

- Updates sending queue worker to save rendered newsletter body
- Updates sending queue router to schedule post notification newsletters

lib/Config/Migrator.php

@@ -214,6 +214,9 @@ class Migrator {
     $attributes = array(
       'id mediumint(9) NOT NULL AUTO_INCREMENT,',
       'newsletter_id mediumint(9) NOT NULL,',
+      'newsletter_rendered_body longtext,',
+      'newsletter_rendered_body_hash varchar(250) NULL DEFAULT NULL,',
+      'newsletter_rendered_subject varchar(250) NULL DEFAULT NULL,',
       'subscribers longtext,',
       'status varchar(12) NULL DEFAULT NULL,',
       'priority mediumint(9) NOT NULL DEFAULT 0,',
@@ -268,4 +271,4 @@ class Migrator {
 
     return implode("\n", $sql);
   }
-}
+}