Clay: ClayModal Body should accept custom className or a scroller

[ambrinchaudhary]

• [x] I have searched the issues of this repository and believe that this is not a duplicate.

What are the steps to reproduce?

There is no way to provide custom classes to the component, i.e:
<ClayModal.Body className="inline-scroller"> is ignored

What is the expected result?

The best solution would be that ClayModal shows a scroll when the content in it's body is too large. This is not happening now, and a possible workaround could be to add a custom className to the modal body

[marcoscv-work]

Inline scroller is here:
http://pat270.github.io/lexicon/v2.16.2/content/modals/#inline-scroller

We have talked with @drakonux and maybe the modal height behavior in inline-scroller is not well defined

[bryceosterhaus]

I'm gonna add a scrollable prop to Modal.Body to add this class