use strict mode when run tap unit test

example/api-ai-bot.js

+var apiai = require('apiai')
+ 
+var app = apiai('7217d7bce18c4bcfbe04ba7bdfaf9c08')
+ 
+var request = app.textRequest('Hello')
+ 
+request.on('response', function(response) {
+    console.log(response)
+})
+ 
+request.on('error', function(error) {
+    console.log(error)
+})
+ 
+request.end()

package.json

@@ -5,7 +5,7 @@
   "main": "index.js",
   "scripts": {
     "start": "node example/ding-dong-bot.js",
-    "test": "TAP_TIMEOUT=120 tap test/*-spec.js",
+    "test": "TAP_TIMEOUT=120 tap --strict test/*-spec.js",
     "lint": "eslint src"
   },
   "repository": {
@@ -39,8 +39,6 @@
     "express": "^4.13.4",
     "npmlog": "^2.0.3",
     "phantomjs-prebuilt": "^2.1.7",
-    "process-tree": "^1.0.0",
-    "retry-promise": "^1.0.0",
     "selenium-webdriver": "",
     "socket.io": "^1.4.5"
   },
@@ -55,7 +53,10 @@
     "node": ">= 6.0.0"
   },
   "devDependencies": {
+    "apiai": "^2.0.5",
     "eslint": "^2.9.0",
+    "process-tree": "^1.0.0",
+    "retry-promise": "^1.0.0",
     "tap": "^5.7.1",
     "tuling123-client": "0.0.1"
   }