It appears that the `required` field is not applied in the way we'd like it to be for the custom checkbox group and custom phone input fields, so do a `required` check on form submission. Additionally, this adds in a few style fixes. Fixes#695, #694, #693, #691
From review of the style with @carljbowman
Requires a bit of magic, where the Form component manually adds the "all" value. But without a major overhaul of the validation system, I don't see how else to put the general error among the other fields.
/cc @carljbowman
One issue we ran into is that our `frameless` configuration is in `em` rather than `rem`, making it difficult to have an aboslute grid applied uniformly at all hierarchies. For now, we're using straight `rem` calculations instead of `$cols{1,8}` in the styling until we can refactor `frameless` to use `em`.
