title: Making gulp-usemin uglify only non-minified files
body: <p>I'd like to have all the Javascript in a single <code>scripts.js</code> files. Here is a portion of my <code>index.html</code>:</p>
  
  <pre><code>&lt;!-- build:inlinejs js/scripts.js --&gt;
  &lt;script src="bower_components/jquery/dist/jquery.min.js"&gt;&lt;/script&gt;
  &lt;script src="bower_components/moment/min/moment.min.js"&gt;&lt;/script&gt;
  &lt;script src="bower_components/moment/locale/de.js"&gt;&lt;/script&gt;
  &lt;script src="bower_components/bootstrap/dist/js/bootstrap.min.js"&gt;&lt;/script&gt;
  &lt;script src="bower_components/eonasdan-bootstrap-datetimepicker/build/js/bootstrap-datetimepicker.min.js"&gt;&lt;/script&gt;
  &lt;script src="js/main.js"&gt;&lt;/script&gt;
  &lt;!-- endbuild --&gt;
  </code></pre>
  
  <p>My current Gulp configuration is as follows:</p>
  
  <pre><code>gulp.task('usemin', function () {
    return gulp.src('./*.html')
        .pipe(usemin({
          css: [minifyCss(), 'concat'],
          html: [minifyHtml({empty: true})],
          js: [uglify(), rev()],
          inlinejs: [uglify()],
          inlinecss: [minifyCss(), 'concat'],
          inline: ['concat']
        }))
        .pipe(gulp.dest('dist/'));
  });
  </code></pre>
  
  <p>As you can see there are already lots of minified Javascript files, so I don't want my build to waste precious time uglifying already minified files. How can I do in order to uglifying only non-minified files?</p>