title: Symfony - How to override a vendor component which is not in a bundle
body: <p>I'm searching for override a file which is in the vendor's directory
  but is not a bundle.
  I'm working with Symfony 2.7</p>
  <p>To be more specific, i'm trying to override a method in this file :</p>
  <pre><code>vendor/akeneo/pim-community-dev/src/Pim/Component/Catalog/Updater/ProductUpdater.php
  </code></pre>
  <p>And I'd like to do it in a file like :</p>
  <pre><code>src/MyApp/Component/Catalog/Updater/ProductUpdater.php
  </code></pre>
  <p>All the documentation I've found is relied to parts of a Bundle.
  So, is it even possible to do that ?
  If it is, how to do it ?</p>