support for ajax-loaded forms

Hi
Everything works fine, except when you load the form dynamically. http://code.google.com/apis/recaptcha/docs/display.html#AJAX 
When you load the form via javascript, the js document.writing the recaptcha doesn't show the recaptcha at all. I made an additional template to handle this case, the solution is dead simple and all you need to run is set CAPTCHA_AJAX (default False) setting.