title: Steps to upgrade in Symfony 2.1 using composer
body: <p>I just testing new features on symfony 2.1-BETA3. Few hours ago BETA4 has been released but I don't know how to update BETA3 to BETA4 using composer. In 2.0.x release notes Fabien said:</p>
  
  <blockquote>
    <p>If you already have a project based on the Symfony Standard Edition 2.0.x, you can easily upgrade to 2.0.15 by getting the new deps and deps.lock files.</p>
  </blockquote>
  
  <p>Have I replace my composer.lock file? What about my own requires like:</p>
  
  <pre><code>"package": "stof/doctrine-extensions-bundle",
  "version": "dev-master",
  "source-reference": "36356b158b74cb68f96dc0b657e8732422b9d5dd",
  "commit-date": "1341954345"
  </code></pre>