title: JSoup.clean() is not preserving relative URLs
body: <p>I have tried:</p>
  
  <pre><code>Whitelist.relaxed();
  Whitelist.relaxed().preserveRelativeLinks(true);
  Whitelist.relaxed().addProtocols("a","href","#","/","http","https","mailto","ftp");
  Whitelist.relaxed().addProtocols("a","href","#","/","http","https","mailto","ftp").preserveRelativeLinks(true);
  </code></pre>
  
  <p>None of them work: When I try to clean a relative url, like <code>&lt;a href="/test.xhtml"&gt;test&lt;/a&gt;</code> I get the <code>href</code> attribute removed (<code>&lt;a&gt;test&lt;/a&gt;</code>).</p>
  
  <p>I am using JSoup 1.8.2.</p>
  
  <p>Any ideas?</p>