multi-checkbox should lay out as column

[Matt Lewellyn]

https://github.com/level12/keg-elements/blob/master/keg_elements/templates/keg_elements/forms/horizontal_b4.html#L134

We use flex-row here, but that was a different layout than what we had for Bootstrap 3. The older template used a ul block to put the checkboxes on rows. flex-row puts multiple checkboxes on a single row, wrapping it around as needed. As a result, the checkboxes are not in a predictable pattern on the page.

We should change that to flex-column when we address some of the other bootstrap-related updates.

[Matt Lewellyn]

Non-issue, the real problem was that the custom css macro wasn't being called, and that provides some additional styling for these checkboxes.