Convert property names to camel case

[MAILPOET-1796]

tests/integration/Models/NewsletterTest.php

@@ -21,9 +21,9 @@ use MailPoetVendor\Carbon\Carbon;
 use MailPoetVendor\Idiorm\ORM;
 
 class NewsletterTest extends \MailPoetTest {
-  public $sending_queue;
-  public $segment_2;
-  public $segment_1;
+  public $sendingQueue;
+  public $segment2;
+  public $segment1;
   public $newsletter;
   public function _before() {
     parent::_before();