Allow forcing the accessibility task to succeed and let Grunt continue

[prantlf]

The Grunt command-line option --force can suppress the failure in any task. However, sometimes it is needed to suppress the failure in just one task and check the result of the other as usual. Tasks usually support their own boolean option force for this.

For example, one instance f the accessibility task could be forced to generate a full report including problems, which have not been fixed yet, while another one could perform the hard check. For example, like this configuration:

  accessibility: {
    'full-report': {
      options: {
        force: true, // ignores the error and lets Grunt continue
        reportType: 'json',
        reportLocation: 'pending'
      },
      src: ['**/*.html']
    },
    'check-fixed': {
      src: ['**/*.html']
    }
  }

used in this task:

  grunt.registerTask('test', [
    'continue:on', 'accessibility:report-all', 'continue:off',
    'accessibility:check-fixed'
  ]);

If the Grunt task should not fail, it must not call grunt.fail.warn, but grunt.log.warn instead. What do you think about supporting the force option like that?