add grunt-pure-grids dependency

Author: tilomitra

package.json

@@ -19,5 +19,8 @@
     "grunt-contrib-watch": "~0.5.3",
     "grunt-css-selectors": "~0.1.0",
     "rework-pure-grids": "0.1.0"
+  },
+  "dependencies": {
+    "grunt-pure-grids": "0.0.1"
   }
 }