Feature Request: Add 'class' field attribute

[dmhendricks]

It would be nice if there was a class attribute on fields and/or if the parent container on settings pages had some sort of common ID or CSS class (such as id="wordpress_settings_api_container" or class="wordpress-settings-api group".

'class' => 'my-custom-class some-other-class',

This would make it easier to do some UI goodness. (On an unrelated note, I kind of wish that the html field type had the option of spanning full-width as opposed to being limited to the second table column.)

Nice work, by the way.