chore(package): update sinon-chai to version 2.13.0

Closes #19

Author: greenkeeper[bot]

package.json

@@ -64,7 +64,7 @@
     "semantic-release": "6.3.6",
     "serve-favicon": "2.4.3",
     "sinon": "2.3.5",
-    "sinon-chai": "2.11.0",
+    "sinon-chai": "2.13.0",
     "strong-error-handler": "2.1.0",
     "validate-commit-msg": "2.12.2"
   },