Bumped to the latest autoprefixer

Author: robneu

config/grunt/postcss.js

@@ -1,5 +1,5 @@
 // https://github.com/nDmitry/grunt-postcss
-var autoprefixer = require( 'autoprefixer-core' );
+var autoprefixer = require( 'autoprefixer' );
 
 module.exports = {
 	options: {

package.json

@@ -15,7 +15,7 @@
     "url": "https://github.com/wpsitecare/sitecare-plugin-config.git"
   },
   "peerDependencies": {
-    "autoprefixer-core": "5.x",
+    "autoprefixer": "6.x",
     "grunt": "0.x",
     "grunt-banner": "0.x",
     "grunt-checktextdomain": "1.x",