title: registering a simple custom task
body: <p>Here is a very simple Gruntfile.js that doesn't produce the output I expect:</p>
  
  <pre><code>module.exports = function (grunt) {
    grunt.registerTask('foo', 'I am foo', function () {
      grunt.log.writeln('test');
    });
  };
  </code></pre>
  
  <p>I run this with "grunt foo" and do not get the output "test".
  Can someone tell me why?</p>