title: Ruby regex: extract a list of urls from a string
body: <p>I have a string of images' URLs and I need to convert it into an array.</p>
  
  <p><a href="http://rubular.com/r/E2a5v2hYnJ" rel="nofollow">http://rubular.com/r/E2a5v2hYnJ</a></p>
  
  <p>How do I do this?</p>