Merge pull request #18 from mix/greenkeeper/initial

Update dependencies to enable Greenkeeper 🌴

package.json

@@ -24,7 +24,7 @@
     "mocha": "~5.2.0",
     "chai": "~4.2.0",
     "sinon": "~7.1.1",
-    "sinon-chai": "~3.2.0",
+    "sinon-chai": "~3.3.0",
     "chai-as-promised": "~7.1.1",
     "jshint": "~2.9.5"
   }