Breaking changes

- Updated to use cf-core which has some basic form styling that needed to be cleared out from here.
- Some formatting fixes like removing unnecessary prefixes and updating syntax.
- Adds some new patterns from cfgov-refresh.

Also let's chat about the custom form elements. My opinion is that each of them should have their own repos. The custom checkboxes and radio in one and the custom select in another. They are two different jQuery plugins that we'll need to write tests and I'd rather do that in separate repos than one large one.
I request bumping this to `4px`. I'd rather the circular validation icons be vertically centered than the email icon. I think the validation icons will be the predominant use case.