add --exit

this is a mochas issue .
mochajs/mocha#2879
This might be better on the long run to simply update dependency version

package.json

@@ -21,7 +21,7 @@
   },
   "scripts": {
     "start": "node server.js",
-    "test": "IP=0.0.0.0 PORT=3030 mocha --timeout 5000 tests/*_test.js"
+    "test": "IP=0.0.0.0 PORT=3030 mocha --timeout 5000 tests/*_test.js --exit"
   },
   "repository": {
     "type": "git",