title: change cssmin and uglify output directories using usemin and grunt
body: <p>When using <code>usemin</code>, the output directory for <code>cssmin</code> and <code>uglifyjs</code> is by default set to <code>dist/assets/</code>.</p>
  
  <p>I want to offer a different directory to place my new files in, ie: <code>assets/</code>.</p>
  
  <p>I can't seem to figure out, how to change these settings in my gruntfile using <code>usemin</code>.</p>