Merge pull request #344 from graphql/greenkeeper/chai-4.1.0

Update chai to the latest version 🚀

Author: wincent

package.json

@@ -78,7 +78,7 @@
     "babel-register": "6.24.1",
     "babel-runtime": "6.23.0",
     "body-parser": "1.17.2",
-    "chai": "3.5.0",
+    "chai": "4.1.0",
     "connect": "3.6.2",
     "coveralls": "2.13.1",
     "eslint": "4.2.0",