title: Periodically scrape and download all images from a website with javascript auto-scroll
body: <p>I have found a website that has lot of high quality free images hosted on Tumblr(It says do whatever you want with theme images :P)</p>
  
  <p>I am running on Ubuntu 12.04LTS. I need to write a script which will run periodically(say daily) and download only the images that were not downloaded earlier. </p>
  
  <p>Additional Note : It has a javascript auto-scroller and the images gets downloaded when you reach the bottom of the page.</p>