title: Regex match spaces in html attribute
body: <p>I have a bunch of html with lines like this:</p>
  
  <p><code>&lt;a href="#" rel="this is a test"&gt;</code></p>
  
  <p>I need to replace the spaces in the rel-attribute with underscores, but I'm sort of a regex-noob!</p>
  
  <p>I'm using Textmate.</p>
  
  <p>Can anyone help me?</p>
  
  <p>/Jakob</p>