title: sass cache busting
body: <p>Is there a way to do file rev cache busting in SASS? It appears to be possible using compass per this answer here:
  <a href="https://stackoverflow.com/questions/975996/sass-image-css-cache-busting-via-compass">SASS Image CSS Cache Busting (via Compass)</a></p>
  
  <p>but I haven't found any way to do this just using SASS.  Is there any way to have SASS get file modification info from the filesystem, and append to an image path?</p>
  
  <p>And I'd prefer to not append query strings- rather, I think this is a better methodology.</p>