title: Recursively convert ES6 to ES5 using babel with grunt
body: <p>My grunt file is as follows :</p>
  
  <pre><code>module.exports = function(grunt) {
  require('load-grunt-tasks')(grunt);
  grunt.initConfig({
  pkg: grunt.file.readJSON('package.json'),
  clean: {
    js: ['src/*.min.js']
  },
  babel: {
     files: {
         expand: true,
         src: ['src/*.js','src/*/*.js','src/*/*/*.js'],
         ext: '-modified.js'
     },
     options: {
         sourceMap: false,
         presets: ['babel-preset-es2015']
     }
  },
   watch: {
    tasks: ['babel']
  }
  
  });
  grunt.registerTask('default', ['clean','babel']);
  };
  </code></pre>
  
  <p>Is there a better way to configure "src" this so that it would recursively find out the js file within src folder and subfolders and transpile those file:</p>
  
  <pre><code> src: ['src/*.js','src/*/*.js','src/*/*/*.js']
  </code></pre>