chore(grunt): add silent mode to grunt

Grunt output can be very annoying. This adds the option to quite Grunt with the '-q' flag.
When ran with '-q', grunt will only output dots for each task action ran successfully
and the error message if something goes wrong.

Gruntfile.js

@@ -4,6 +4,10 @@
 
 module.exports = function (grunt) {
 
+  if (grunt.option('q') || grunt.option('quiet')) {
+    require('quiet-grunt');
+  }
+
   // Project configuration.
   var config = {
     pkg: grunt.file.readJSON('package.json'),

package.json

@@ -47,6 +47,7 @@
     "grunt-simple-mocha": "^0.4.0",
     "js-beautify": "^1.5.6",
     "load-grunt-tasks": "^3.2.0",
+    "quiet-grunt": "^0.2.3",
     "sinon": "^1.14.1",
     "source-map-support": "^0.2.9"
   }