chore(package): update grunt-contrib-clean to version 2.0.0

Author: greenkeeper[bot]

package.json

@@ -13,7 +13,7 @@
     "angular-mocks": "^1.2.24",
     "grunt": "^1.0.1",
     "grunt-cli": "^1.2.0",
-    "grunt-contrib-clean": "^1.0.0",
+    "grunt-contrib-clean": "^2.0.0",
     "grunt-contrib-concat": "^1.0.1",
     "grunt-contrib-copy": "^1.0.0",
     "grunt-contrib-uglify": "^3.0.0",