chore(package): update mocha to version 4.1.0

Closes #8

Author: greenkeeper[bot]

package.json

@@ -13,7 +13,7 @@
   "devDependencies": {
     "assume": "~1.5.0",
     "istanbul": "~0.4.5",
-    "mocha": "~3.5.0",
+    "mocha": "~4.1.0",
     "negotiation": "0.0.x",
     "pre-commit": "~1.2.0",
     "transport-layer": "0.0.x"