title: Gulp concatening multiple actions
body: <p>I get the following error when i run this</p>
  
  <pre><code>gulp.task('gen:enemies', function () {
    /**
     *  Hold all directories names starting with "enemy"
     */
    var EnemyDirs = fs.readdirSync(path.join('images')).filter(function (p) {
        if (p.match(/^enemy/)) {
          return fs.readdirSync(path.join('images', p));
        }
      });
    /**
     *  Run action for every directory found
     */
    var EnemyBuildAction = EnemyDirs.map(function (_dir) {
        // Get all images in directory
        return gulp.src(path.join('images', _dir, '*.png'))
        .pipe(sprite({ // build sprite
            'name' : [_dir, '.png'].join(''),
            'orientation' : 'horizontal'
        }))
        .pipe(gulpif('*.png', gulp.dest(path.join('build')))); // output
      });
    return es.concat.apply(null, EnemyBuildAction); // concat actions
  });
  </code></pre>
  
  <p>Maximum event listeners reached..</p>
  
  <p>The directory structure is quite large, like</p>
  
  <pre>
  images\
         enemy.bat\
                   1.png
                   2.png
                   3.png
  </pre>
  
  <p>There are like 50 enemy directories with multiple <code>.png</code> files.</p>
  
  <p>What can i do to avoid the max listeners error?</p>