chore(package): update mocha to version 3.4.1

Closes graphql#184

Author: greenkeeper[bot]

package.json

@@ -83,7 +83,7 @@
     "flow-bin": "0.46.0",
     "graphql": "^0.9.6",
     "jsdom": "10.1.0",
-    "mocha": "3.3.0",
+    "mocha": "3.4.1",
     "sane": "1.6.0"
   }
 }