Update grunt-contrib-qunit to version 2.0.0

Closes js-cookiegh-322.

Author: greenkeeperio-bot

package.json

@@ -32,7 +32,7 @@
     "grunt-contrib-connect": "1.0.2",
     "grunt-contrib-jshint": "1.1.0",
     "grunt-contrib-nodeunit": "1.0.0",
-    "grunt-contrib-qunit": "1.3.0",
+    "grunt-contrib-qunit": "2.0.0",
     "grunt-contrib-uglify": "2.2.1",
     "grunt-contrib-watch": "1.0.0",
     "grunt-jscs": "3.0.1",