title: Symfony2 Yaml Dumper single quote escaping
body: <p>I've got some csv translations that are transformed and written into messages.fr.yml with Symfony\Component\YamlDumper, and on strings like <strong>d'achat</strong> it becomes <strong>'d''achat'</strong>.</p>
  
  <p>I've done some debugging and discovered that the string is recognized as the one that needs escaping:</p>
  
  <pre><code>preg_match('/[ \s \' " \: \{ \} \[ \] , &amp; \* \# \?] | \A[ \- ? | &lt; &gt; = ! % @ ` ]/x', $value)
  </code></pre>
  
  <p>and then escaped with the following code:</p>
  
  <pre><code>return sprintf("'%s'", str_replace('\'', '\'\'', $value));
  </code></pre>
  
  <p>I already tried using function addslashes before the debugging, but this escaping is not recognized.</p>
  
  <p>So I'd like to know the opinion of the Symfony community: is it a bug or is it a feature? Should I report it and fix or just check my inputs and replace single quotes (') with apostrophe (’)?</p>