title: How to add button to "submit_row" context in django
body: <p>I would like to add an extra button to the submit row in django. 
  Standard we get "delete", "save", "save and continue editing" and "save and add another". To this set I would like to add another button which would call a function on the model. </p>
  
  <p>As far as I understand the template <code>change_form</code> is generated in one of the <code>admin.views</code>. The context <code>submit_row</code> is passed as context. </p>
  
  <p>I want to edit the context of the admin view. Where can I find it in my filesystem?</p>