Fix processing of SCSS with Grunt

We now use the Ruby implementation of SASS (grunt-contrib-sass) since
libsass is not compatible with Compass.

UI/WebServerResources/package.json

@@ -3,10 +3,9 @@
     "version": "0.0.1",
     "devDependencies": {
         "bower": ">=1.3.8",
-        "node-sass": ">=0.7.0",
         "grunt": ">=0.4.1",
         "grunt-cli": ">=0.1.11",
         "grunt-contrib-watch": ">=0.5.3",
-        "grunt-sass": ">=0.8.0"
+        "grunt-contrib-sass": ">=0.8.0"
     }
 }