add reference to mocha library

Author: tiagoschenkel

test/entry.ts

@@ -5,6 +5,8 @@
 //  in accordance with the terms of the license agreement accompanying it.
 // ------------------------------------------------------------------------------
 
+/// <reference types="mocha" />
+
 import "reflect-metadata";
 import "bluebird/js/browser/bluebird";
 import "es6-symbol/implement";