fixes defective file handling, uses grunt logging now, pass options on t...

The current task fails to handle a file config like below. This patch also replaces console.log by grunt.log for less-verbose logging if not needed.

    traceur: {
        custom: {
          files: [
            {
              expand: true,
              cwd: 'scripts/',
              src: '**/*.js',
              dest: 'build/scripts/'
            }
          ]
        }
      }