- Moves Import and Export under ImportExport namespace

- Cretes a single BootStrapMenu class for Import and Export
- Updates tests
- Adds 2 new methods to Segments model

lib/Config/Menu.php

@@ -1,6 +1,7 @@
 <?php
 namespace MailPoet\Config;
 
+use MailPoet\ImportExport\BootStrapMenu;
 use \MailPoet\Models\Segment;
 use \MailPoet\Models\Setting;
 use \MailPoet\Models\Form;
@@ -236,13 +237,15 @@ class Menu {
   }
 
   function import() {
-    $import = new \MailPoet\Import\BootstrapMenu();
+    $import = new BootStrapMenu('import');
     $data = $import->bootstrap();
     echo $this->renderer->render('import.html', $data);
   }
 
   function export() {
-    echo $this->renderer->render('export.html');
+    $export = new BootStrapMenu('export');
+    $data = $export->bootstrap();
+    echo $this->renderer->render('export.html', $data);
   }
 
   function formEditor() {