Should headings null paragraph styles?

Currently, headings nullify any character styles. For example: if you have a heading that is bold, you don't end up with `<h1><strong>Heading</strong></h1>`.

Do we want to do the same for paragraph styles? This includes text alignment and indentation, which will appear as spans within the header: `<h1><span class='pydocx-center'>Heading</span></h1>`
