chore(package): update sinon to version 2.3.2

Closes #29

Author: greenkeeper[bot]

package.json

@@ -76,7 +76,7 @@
     "less": "^2.7.2",
     "mocha": "^3.2.0",
     "selenium-webdriver": "3.3.0",
-    "sinon": "2.1.0",
+    "sinon": "2.3.2",
     "sinon-chai": "2.9.0",
     "source-map-support": "0.4.14",
     "stream-browserify": "^2.0.1"