'className' Common Field Property

[brownhoward]

User Story

As a Form Designer, I want to specify the CSS class that should be applied when a data element is rendered, so I can use specific styling.

Acceptance Criteria

1. In the Form Model describing the form, I can set a 'className' property on any form data element to specify that references a CSS class.
2. When the form is rendered based on the Form Model, the referenced CSS class is used to style the data element.

[timbl]

Maybe htmlClass to distinguish from RDF classes?