title: Translation label for Choice field are not working in Sonata Admin Datagrid filter
body: <p>I'm using Sonata Admin Bundle with Sonata User Bundle in my Symfony 2.7 application. I have a Property Admin page. Here is its configuration in my services.yml:</p>
  
  <pre><code>// ...
  mybundle.admin.property:
      class: MyBundle\Admin\PropertyAdmin
      tags:
          - { name: sonata.admin, manager_type: orm, group: Property, label: Properties }
      arguments:
          - ~
          - MyBundle\Entity\Property
          - 'MyBundle:PropertyAdmin'
  </code></pre>
  
  <p>I added two custom action buttons in the property admin list. I had to add two translation strings <code>action_rooms</code> and <code>action_stations</code> for those two buttons in <code>app/Resource/SonataAdminBundle/translations/SonataAdminBundle.en.xliff</code> which I copied from <code>vendor/sonata-project/admin-bundle/Sonata/AdminBundle/Resources/translations/SonataAdminBundle.en.xliff</code>. They are working fine.</p>
  
  <p>The problem is that translation for <code>label_type_yes</code> and <code>label_type_no</code> in the datagrid filter is not working although they are defined in <code>SonataAdminBundle.en.xliff</code>. Here is the screen shot of the property list.</p>
  
  <p><img src="https://i.stack.imgur.com/pBCZD.png" alt="enter image description here"></p>
  
  <p>I created <code>app/Resources/translations/MyBundle.en.xliff</code> with the content of <code>SonataAdminBundle.en.xliff</code> and I added <code>setTranslationDomain</code> in <code>services.yml</code> for <code>mybundle.admin.property</code>, but no success.</p>
  
  <pre><code>    calls:
          - [setTranslationDomain, ['MyBundle']]
  </code></pre>
  
  <p>They are not also working in the user list <code>/admin/sonata/user/user/list</code> that is generated by Sonata User Bundle. I notice that it was not working before I created <code>app/Resource/SonataAdminBundle/translations/SonataAdminBundle.en.xliff</code>.</p>
  
  <p><img src="https://i.stack.imgur.com/19JT0.png" alt="enter image description here"></p>
  
  <p>I have the translator enabled in config.yml and parameters.yml.</p>
  
  <pre><code>// config.yml
  framework:
      translator:      { fallbacks: ["%locale%"] }
  
  // parameters.yml
  parameters:
      // ..
      locale: en
  </code></pre>