bump grunt-css-flip to ~0.2.2

package.json

@@ -49,7 +49,7 @@
     "grunt-contrib-uglify": "~0.4.0",
     "grunt-contrib-watch": "~0.6.1",
     "grunt-csscomb": "~2.0.1",
-    "grunt-css-flip": "~0.2.1",
+    "grunt-css-flip": "~0.2.2",
     "grunt-exec": "~0.4.5",
     "grunt-html-validation": "~0.1.15",
     "grunt-jekyll": "~0.4.1",