Upgrade dev dependency jscs

But stick with a 2.x.x branch as upgrading to 3.x.x broke things.

Author: rjmunro

package.json

@@ -50,7 +50,7 @@
   "devDependencies": {
     "chai": "4.1.2",
     "istanbul": "0.4.5",
-    "jscs": "1.13.1",
+    "jscs": "2.11.0",
     "jshint": "2.9.5",
     "mocha": "5.1.1"
   },