title: Asset Paths Broken After Upgrade to Rails 4
body: <p>I have upgraded from 3.2 to 4. But assets are broken. </p>
  
  <p>I have been using "assets/img/work/1.jpg" but I can't access to them in this way now. I can only access with digest like "assets/img/work/1-90041f6a6f670bd667cbfb47a50b27d2.jpg" what should i do? Only way is using image_tag? </p>
  
  <p>Is using erb in CSS and JS files cause performance issues?</p>