Form editor

- new/edit in forms listing goes to editor
- fixed editor dependencies (via Webpack)
- updated forms table schema
- saving/loading a form works

lib/Form/Block/Divider.php

@@ -0,0 +1,9 @@
+<?php
+namespace MailPoet\Form\Block;
+
+class Divider {
+
+  static function render() {
+    return '<hr class="mailpoet_divider" />';
+  }
+}