add timeout to mocha grunt job

Gruntfile.js

@@ -61,6 +61,7 @@ module.exports = function(grunt) {
         mocha: {
             all: {
                 options: {
+                    timeout: 20000,
                     urls: ['http://localhost:<%= connect.test.options.port %>/test/new-unit/index.html'],
                     run: false
                 }