Add intern testing framework

package.json

@@ -20,6 +20,7 @@
     "gulp": "^3.9.1",
     "gulp-tslint": "^7.1.0",
     "gulp-typescript": "^3.1.5",
+    "intern": "^3.4.2",
     "tslint": "^4.4.2",
     "typescript": "^2.1.6"
   },