Update clean-css to v4.1.1.

CHANGELOG

@@ -1,3 +1,7 @@
+v2.2.0:
+  date: 2017-05-10
+  changes:
+    - Update clean-css to v4.1.1.
 v2.1.0:
   date: 2017-04-17
   changes:

README.md

@@ -1,4 +1,4 @@
-# grunt-contrib-cssmin v2.1.0 [![Build Status: Linux](https://travis-ci.org/gruntjs/grunt-contrib-cssmin.svg?branch=master)](https://travis-ci.org/gruntjs/grunt-contrib-cssmin) [![Build Status: Windows](https://ci.appveyor.com/api/projects/status/ntgfqc3ppk533m84/branch/master?svg=true)](https://ci.appveyor.com/project/gruntjs/grunt-contrib-cssmin/branch/master)
+# grunt-contrib-cssmin v2.2.0 [![Build Status: Linux](https://travis-ci.org/gruntjs/grunt-contrib-cssmin.svg?branch=master)](https://travis-ci.org/gruntjs/grunt-contrib-cssmin) [![Build Status: Windows](https://ci.appveyor.com/api/projects/status/ntgfqc3ppk533m84/branch/master?svg=true)](https://ci.appveyor.com/project/gruntjs/grunt-contrib-cssmin/branch/master)
 
 > Minify CSS
 
@@ -86,6 +86,7 @@ cssmin: {
 
 ## Release History
 
+ * 2017-05-10   v2.2.0   Update clean-css to v4.1.1.
  * 2017-04-17   v2.1.0   Set required Node.js version to >=4 since clean-css 4.x requires that.
  * 2017-02-02   v2.0.0   Update clean-css to v4.0.3.
  * 2016-08-31   v1.0.2   Fix issues for node 6.
@@ -119,4 +120,4 @@ cssmin: {
 
 Task submitted by [Tim Branyen](http://tbranyen.com/)
 
-*This file was generated on Mon Apr 17 2017 16:05:09.*
+*This file was generated on Wed May 10 2017 18:02:52.*

package.json

@@ -1,7 +1,7 @@
 {
   "name": "grunt-contrib-cssmin",
   "description": "Minify CSS",
-  "version": "2.1.0",
+  "version": "2.2.0",
   "author": {
     "name": "Grunt Team",
     "url": "http://gruntjs.com/"
@@ -17,7 +17,7 @@
   },
   "dependencies": {
     "chalk": "^1.0.0",
-    "clean-css": "~4.0.12",
+    "clean-css": "~4.1.1",
     "maxmin": "^2.1.0"
   },
   "devDependencies": {