title: rename templates folders with a gruntjs custom init task
body: <p>I'm trying to create a custom <em>init task</em> for a personal template in <a href="https://github.com/cowboy/grunt" rel="nofollow">Grunt</a>.</p>
  
  <p>This is the js which generate my new project after a <code>grunt init:mytemplate</code></p>
  
  <pre><code>exports.description = 'Try Grunt';
  exports.warnOn = '*';
  
  exports.template = function(grunt, init, done) {
    grunt.helper('prompt', {type: 'skin'}, [
      grunt.helper('prompt_for', 'name', 'trygrunt'),
      grunt.helper('prompt_for', 'title', 'Im Trying GruntJS'),
      grunt.helper('prompt_for', 'author_name', 'Myself')
    ],
    function(err, props) {
      var files = init.filesToCopy(props);
      init.copyAndProcess(files, props);
      done();
    });
  };
  </code></pre>
  
  <p>Everything works fine: files and folder are correctly generated or renamed from the <code>root</code> folder of the custom template based on <code>rename.json</code> info.</p>
  
  <p>The question is: how can i also dynamically rename folders and not only files?</p>
  
  <p>i.e.</p>
  
  <pre><code>{
      "libs/name.js": "libs/{%= name %}.js" //this works fine
      "src/name": "src/{%= name %}" //this doesn't work
  }
  </code></pre>