title: Run grunt build command on Travis CI
body: <p>I am using Travis CI to test and build my project and as part of it I want travis to run <code>grunt build</code> i have tried the following but have had no luck.</p>
  
  <ul>
  <li><code>script: "grunt build"</code></li>
  <li><code>script: "./node_modules/grunt build"</code></li>
  <li><code>script: "./node_modules/grunt/grunt build"</code></li>
  <li><code>script: "./node_modules/grunt/grunt.js build"</code></li>
  </ul>