removed grunt-contrib-clean

gruntfile.js

 module.exports = function(grunt) {
     'use strict';
 
-    grunt.loadNpmTasks('grunt-contrib-clean');
     grunt.loadNpmTasks('grunt-contrib-watch');
     grunt.loadNpmTasks('grunt-contrib-jshint');
 
     grunt.initConfig({
-        clean: {
-            coverage: ['coverage/**']
-        },
         jshint: {
             options: {
                 jshintrc: true

package.json

@@ -10,7 +10,6 @@
   "dependencies": {},
   "devDependencies": {
     "grunt": "^0.4.5",
-    "grunt-contrib-clean": "^0.6.0",
     "grunt-contrib-jshint": "^0.11.0",
     "grunt-contrib-watch": "^0.6.1",
     "istanbul": "^0.3.0",