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="Header_Reseller_(Admin).png" />
  </query-continue>
  <query>
    <pages>
      <page pageid="4" ns="6" title="File:2011 Cloud Computing - Chancen und Risiken.pdf" />
      <page pageid="20" ns="6" title="File:Automation in the Cloud – Using Open Source Software.pdf" />
      <page pageid="8" ns="6" title="File:Cloud Management und Automatisierung 2013.pdf" />
      <page pageid="156" ns="6" title="File:Daemon-communication.png" />
      <page pageid="300" ns="6" title="File:Daemon-communication.xmi" />
      <page pageid="158" ns="6" title="File:Daemon-interaction-restore.png" />
      <page pageid="5" ns="6" title="File:FOSS-Cloud.pdf" />
      <page pageid="173" ns="6" title="File:Header Customer (Admin).png" />
      <page pageid="174" ns="6" title="File:Header Customer (User).png" />
      <page pageid="171" ns="6" title="File:Header Provider (Admin).png" />
    </pages>
  </query>
</api>