title: How to omit devDependencies when copying node_modules?
body: <p>I'd like to copy only modules, which are important for application - those located inside <code>dependencies</code> in <code>package.json</code>. I'd like to omit those under <code>devDependencies</code>.</p>
  
  <p><code>package.json</code></p>
  
  <pre><code>{            
      "dependencies": {
          "express": "^4.13.4",
          "log4js": "^0.6.33"            
      },
      "devDependencies": {
          "gulp": "^3.9.1",
          "gulp-rename": "^1.2.2",
          "gulp-typescript": "^2.12.1",
          "typings": "^0.7.9",
          "yargs": "^4.3.2"
      }
  }
  </code></pre>
  
  <p><code>gulpfile.js</code></p>
  
  <pre><code>gulp.task('copy_packages', function() {
        gulp
           .src('node_modules/**/*.*')
           .pipe(gulp.dest('../release/node_modules'));
  });
  </code></pre>
  
  <p>Is there any module or a  smart way to distinguish which modules belongs to <code>dependencies</code> group and which to <code>devDependencies</code>?</p>