title: The requested PHP extension intl is missing from your system (SonataAdminBundle) in Symfony2
body: <p>I try to install the sandbox but I get the following error from composer:</p>
  
  <blockquote>
    <p>Loading composer repositories with package information Installing
    dependencies from lock file Your requirements could not be resolved to
    an installable set of packages.</p>
  </blockquote>
  
  <p>Problem 1</p>
  
  <pre><code>- Installation request for sonata-project/intl-bundle 2.1.0 -&gt; satisfiable by sonata-project/intl-bundle 2.1.0.`
  
  - sonata-project/intl-bundle 2.1.0 requires ext-intl * -&gt; the requested PHP extension intl is missing from your system.`
  </code></pre>
  
  <p>Problem 2</p>
  
  <pre><code>- sonata-project/intl-bundle 2.1.0 requires ext-intl * -&gt; the requested PHP extension intl is missing from your system.`
  
  - sonata-project/news-bundle 2.1.x-dev requires sonata-project/intl-bundle 2.1.* -&gt; satisfiable by sonata-project/intl-bundle 2.1.0.
  - Installation request for sonata-project/news-bundle 2.1.
  </code></pre>