title: Inserting HTML Form using CKeditor does not work
body: <p>I'm having a big issue using Ckeditor..
  I want that my customer can add a paypal donation button trough a personnalised page.
  When my customer want to add a customized page they use ckeditor.</p>
  
  <p>To add a paypal button, they would have to  just copy / Paste the following code using the source mode:</p>
  
  <pre><code>&lt;form action="https://www.paypal.com/cgi-bin/webscr" method="post"&gt;
  &lt;input type="hidden" name="cmd" value="_donations"&gt;
  &lt;input type="hidden" name="business" value="try@try.com"&gt;
  &lt;input type="hidden" name="lc" value="US"&gt;
  &lt;input type="hidden" name="item_name" value="Try"&gt;
  &lt;input type="hidden" name="no_note" value="0"&gt;
  &lt;input type="hidden" name="currency_code" value="EUR"&gt;
  &lt;input type="hidden" name="bn" value="PP-DonationsBF:btn_donateCC_LG.gif:NonHostedGuest"&gt;
  &lt;input type="image" src="https://www.paypalobjects.com/fr_XC/i/btn/btn_donateCC_LG.gif" border="0" name="submit" alt="PayPal - la solution de paiement en ligne la plus simple et la plus sécurisée !"&gt;
  &lt;img alt="" border="0" src="https://www.paypalobjects.com/fr_XC/i/scr/pixel.gif" width="1" height="1"&gt;
  &lt;/form&gt;
  </code></pre>
  
  <p>However when they save the, somehow the html is modifyed with this one:</p>
  
  <pre><code>&lt;form action="https://www.paypal.com/cgi-bin/webscr" method="post"&gt;
      &amp;nbsp;&lt;/form&gt;
  </code></pre>
  
  <p>I dont know how to avoid this.
  I think it's an option in CKeditor config which is replacing some html codes but i'm not sure. </p>
  
  <p>Thanks a lot for your futur advices,</p>
  
  <p>Anselme</p>