Render multiple files with globbing

See issue #1. Now we can do something like

```
    htmlbuild: {
      dist: {
        src: 'html/*.html',
        dest: 'dist/',
        options: {
          beautify: true,
          sections: {
            banner: 'html/templates/banner.html',
            analytics: 'html/templates/analytics.html',
          }
        }
      }
    }
```