title: Gruntfile fails with Warning: Task "taskname" not found
body: <p>This happens with whatever task I'm trying to run.
  When running with <code>--verbose</code> flag I'm getting:</p>
  
  <blockquote>
    <p>Initializing Command-line options: --verbose</p>
    
    <p>Reading "Gruntfile.js" Gruntfile...OK</p>
    
    <p>Registering Gruntfile tasks. Loading "Gruntfile.js" tasks...OK</p>
    
    <blockquote>
      <blockquote>
        <p>No tasks were registered or unregistered.</p>
      </blockquote>
    </blockquote>
  </blockquote>
  
  <p>This is the Gruntfile:</p>
  
  <pre class="lang-js prettyprint-override"><code>module.export = function (grunt) {
  
      grunt.initConfig({
          pkg: grunt.file.readJSON('package.json'),
  
          karma_coveralls: {
              options: {
                  coverage_dir: 'coverage'
              }
          },
          jshint: {
              files: ['app/js/**/*.js', 'Gruntfile.js'],
              options: grunt.file.readJSON('.jshintrc')
          },
          concat: {
              options: {
                  seperator: ';'
              },
              dist: {
                  src: ['app/js/**/*.js'],
                  dest: 'dist/app/js/&lt;%pkg.name%&gt;.js'
              }
          },
          exec: {
              instrument: {
                  cmd: function () {
                      return 'istanbul instrument app/js -o app/instrumentjs';
                  }
              }
          }
      });
  
      grunt.loadNpmTasks('grunt-karma-coveralls');
      grunt.loadNpmTasks('grunt-contrib-jshint');
      grunt.loadNpmTasks('grunt-contrib-watch');
      grunt.loadNpmTasks('grunt-contrib-concat');
      grunt.loadNpmTasks('grunt-contrib-watch');
      grunt.registerTask('coverage', ['coveralls']);
      grunt.registerTask('default', ['jshint']);
      grunt.registerTask('instrument', ['exec: instrument']);
      grunt.registerTask('concat', ['concat']);
  
  };
  </code></pre>
  
  <p>Any Idea what am I doing wrong?</p>
  
  <p>grunt versions:</p>
  
  <p>grunt-cli v0.1.9
  grunt v0.4.1</p>