title: Unable to add custom tasks to Sails.js Gruntfile
body: <p>I'm new to Sails.js and I'm having issues adding additional tasks to it's gruntfile. What I'm trying to do is use autoprefixer with Less, but everytime I call "sails lift" I get the following error:</p>
  
  <p><code>error: Grunt :: Warning: Task "autoprefixer:multiple_files" not found. Use --force to continue.</code></p>
  
  <p><code>&gt;&gt; Tasks directory "grunt-autoprefixer" not found.</code></p>
  
  <p>Here's the lines I added to the gruntfile:</p>
  
  <p><code>grunt.loadTasks('grunt-autoprefixer');</code></p>
  
  <pre><code>grunt.initConfig({
    autoprefixer: {
      options: {
        browsers: ['last 2 version', 'ie 8', 'ie 7']
      },
      multiple_files: {
        expand: true,
        flatten: true,
        src: 'assets/linker/styles/*.css',
        dest: 'assets/linker/styles/'
      },
      concat: {
        src: 'assets/linker/styles/*.css',
        dest: 'assets/linker/styles/s.css'
      }
    },
  //Rest of initConfig...
  
  //compileAssets task
  grunt.registerTask('compileAssets', [
    'clean:dev',
    'jst:dev',
    'less:dev',
    'autoprefixer:multiple_files',
    'copy:dev',    
    'coffee:dev'
   ]);
  </code></pre>
  
  <p>I've tried removing "multiple_files" from the compileAssets task. I've tried installing autoprefixer both locally and globally but no dice, always the same error.</p>
  
  <p>Any ideas?</p>
  
  <p>Thanks!</p>