Use grunt API for mkdir and rm

Gruntfile.coffee

@@ -1,7 +1,5 @@
 fs = require 'fs'
 path = require 'path'
-rm = require('rimraf').sync
-mkdir = require('wrench').mkdirSyncRecursive
 _ = require 'underscore'
 CSON = require 'season'
 
@@ -22,6 +20,9 @@ module.exports = (grunt) ->
       grunt.file.copy(source, destination)
     grunt.log.writeln("Copied #{source.cyan} to #{destination.cyan}.")
 
+  mkdir = (args...) -> grunt.file.mkdir(args...)
+  rm = (args...) -> grunt.file.delete(args..., force: true)
+
   grunt.initConfig
     pkg: grunt.file.readJSON('package.json')
 

package.json

@@ -66,8 +66,6 @@
     "grunt-cli": "~0.1.9",
     "grunt-coffeelint": "0.0.6",
     "grunt-contrib-csslint": "~0.1.2",
-    "rimraf": "~2.1.4",
-    "wrench": "~1.5.1",
     "grunt-contrib-coffee": "~0.7.0",
     "grunt-contrib-less": "~0.5.2"
   },