You are looking at the HTML representation of the XML format.
HTML is good for debugging, but is unsuitable for application use.
Specify the format parameter to change the output format.
To see the non HTML representation of the XML format, set format=xml.
See the complete documentation, or API help for more information. 
<?xml version="1.0"?>
<api>
  <query-continue>
    <allimages gaicontinue="isp_weiter_email.png" />
  </query-continue>
  <query>
    <pages>
      <page pageid="16" ns="6" title="Datei:Vertrag Profi1-Tomcat 2014 de.pdf" imagerepository="local">
        <imageinfo>
          <ii timestamp="2015-10-12T14:06:38Z" user="Nschollum" />
        </imageinfo>
      </page>
      <page pageid="54" ns="6" title="Datei:isp mail kon mail.png" imagerepository="local">
        <imageinfo>
          <ii timestamp="2015-11-20T12:01:55Z" user="Tschwaab" />
        </imageinfo>
      </page>
      <page pageid="56" ns="6" title="Datei:isp sammelmail.png" imagerepository="local">
        <imageinfo>
          <ii timestamp="2015-11-20T14:01:35Z" user="Tschwaab" />
        </imageinfo>
      </page>
      <page pageid="57" ns="6" title="Datei:isp web neu.png" imagerepository="local">
        <imageinfo>
          <ii timestamp="2015-11-20T15:17:33Z" user="Tschwaab" />
        </imageinfo>
      </page>
    </pages>
  </query>
</api>