title: Grunt isn't updating scripts when saving changes
body: <p>I'm totally new to <code>Grunt</code>, I'm using the <code>Roots</code> <code>Wordpress</code> starter theme which has an included <code>Gruntfile.js</code> like so:</p>
  
  <pre><code>'use strict';
  module.exports = function(grunt) {
  
    grunt.initConfig({
      jshint: {
        options: {
          jshintrc: '.jshintrc'
        },
        all: [
          'Gruntfile.js',
          'assets/js/*.js',
          '!assets/js/scripts.min.js'
        ]
      },
      less: {
        dist: {
          files: {
            'assets/css/main.min.css': [
              'assets/less/app.less'
            ]
          },
          options: {
            compress: true,
            // LESS source map
            // To enable, set sourceMap to true and update sourceMapRootpath based on your install
            sourceMap: false,
            sourceMapFilename: 'assets/css/main.min.css.map',
            sourceMapRootpath: '/app/themes/roots/'
          }
        }
      },
      uglify: {
        dist: {
          files: {
            'assets/js/scripts.min.js': [
              'assets/js/plugins/bootstrap/transition.js',
              'assets/js/plugins/bootstrap/alert.js',
              'assets/js/plugins/bootstrap/button.js',
              'assets/js/plugins/bootstrap/carousel.js',
              'assets/js/plugins/bootstrap/collapse.js',
              'assets/js/plugins/bootstrap/dropdown.js',
              'assets/js/plugins/bootstrap/modal.js',
              'assets/js/plugins/bootstrap/tooltip.js',
              'assets/js/plugins/bootstrap/popover.js',
              'assets/js/plugins/bootstrap/scrollspy.js',
              'assets/js/plugins/bootstrap/tab.js',
              'assets/js/plugins/bootstrap/affix.js',
              'assets/js/plugins/*.js',
              'assets/js/_*.js'
            ]
          },
          options: {
            // JS source map: to enable, uncomment the lines below and update sourceMappingURL based on your install
            // sourceMap: 'assets/js/scripts.min.js.map',
            // sourceMappingURL: '/app/themes/roots/assets/js/scripts.min.js.map'
          }
        }
      },
      version: {
        options: {
          file: 'lib/scripts.php',
          css: 'assets/css/main.min.css',
          cssHandle: 'roots_main',
          js: 'assets/js/scripts.min.js',
          jsHandle: 'roots_scripts'
        }
      },
      watch: {
        less: {
          files: [
            'assets/less/*.less',
            'assets/less/bootstrap/*.less'
          ],
          tasks: ['less', 'version']
        },
        js: {
          files: [
            '&lt;%= jshint.all %&gt;'
          ],
          tasks: ['jshint', 'uglify', 'version']
        },
        livereload: {
          // Browser live reloading
          // https://github.com/gruntjs/grunt-contrib-watch#live-reloading
          options: {
            livereload: false
          },
          files: [
            'assets/css/main.min.css',
            'assets/js/scripts.min.js',
            'templates/*.php',
            '*.php'
          ]
        }
      },
      clean: {
        dist: [
          'assets/css/main.min.css',
          'assets/js/scripts.min.js'
        ]
      }
    });
  
    // Load tasks
    grunt.loadNpmTasks('grunt-contrib-clean');
    grunt.loadNpmTasks('grunt-contrib-jshint');
    grunt.loadNpmTasks('grunt-contrib-uglify');
    grunt.loadNpmTasks('grunt-contrib-watch');
    grunt.loadNpmTasks('grunt-contrib-less');
    grunt.loadNpmTasks('grunt-wp-version');
  
    // Register tasks
    grunt.registerTask('default', [
      'clean',
      'less',
      'uglify',
      'version'
    ]);
    grunt.registerTask('dev', [
      'watch'
    ]);
  
  };
  </code></pre>
  
  <p>From what I can see, <code>Grunt</code>should be watching for changes to anything in my <code>/assets/js/*</code> folder.</p>
  
  <p>However, when I:</p>
  
  <ul>
  <li>Add a new script, like <code>/assets/js/plugins/jquery-thing.js</code></li>
  <li>Update a script, like <code>/assets/js/_main.js</code></li>
  </ul>
  
  <p>It doesn't properly update nor compile the scripts into <code>scripts.min.js</code>. )I think this is the <code>uglify</code> operation, for what it's worth).</p>
  
  <p>Any idea what's going wrong here? I'm updating these files but Wordpress is just pulling in very old script versions. I've tried replacing the <code>gruntfile</code> with a fresh one from the <code>Roots</code> github page, but to no avail.</p>
  
  <p>EDIT: I have <code>grunt watch</code> running in console, just to state the obvious.</p>