title: grunt.util.spawn doesn't give output
body: <p>Grunt.util.spawn is not calling the done function. Here is the code. when the command gets executed from command prompt it is failing and throws an error message which is not captured in gruntjs..what is happening</p>
  
  <pre><code>module.exports = (grunt)-&gt;
  grunt.initConfig
      concurrent:
          dev: ['watch']
      slim:
          dev:
              expand: true
              src:  'views'
              dest: 'views/'
      watch:
          slim:
              files: 'views/**.slim'
              tasks:['slim']
  
  grunt.registerMultiTask 'slim', 'Server Slim Compiler', -&gt;
      console.log 'In the slim'
      options = {}
      options.cmd = 'dirld'
      options.grunt = true
      console.log options
      grunt.util.spawn options, (err,res,cod)-&gt;
          console.log 'in the spawn'
          if err
              grunt.log.error err
          else
              grunt.log.oklns 'success'
              grunt.log.writeln res
  
  grunt.loadNpmTasks 'grunt-contrib-watch'
  grunt.loadNpmTasks 'grunt-concurrent'
  grunt.registerTask 'default', ['concurrent:dev']
  </code></pre>