Merge pull request #20 from textpattern/greenkeeper/grunt-postcss-0.9.0

Update grunt-postcss to the latest version 🚀

Author: philwareham

package.json

@@ -26,7 +26,7 @@
     "grunt-contrib-cssmin": "2.2.1",
     "grunt-contrib-jshint": "1.1.0",
     "grunt-contrib-watch": "1.0.0",
-    "grunt-postcss": "0.8.0",
+    "grunt-postcss": "0.9.0",
     "grunt-sass": "2.0.0",
     "grunt-sass-lint": "0.2.3",
     "load-grunt-tasks": "~3.5",