Reapply vertical spacing fixes to 6.2.x, add integration test case

[shawnbot]

This is a (manual) re-application the blue background and vertical spacing fixes originally introduced in #109, but without the weird regression documented in #119.

Current status

• Something in the 6.3.0 release (#109) broke this form in such a way that it's impossible to move past the 3rd page
• sf.gov is stuck on 6.2.1 until this issue is resolved
• I was hoping to plow ahead to the 7.0 release (#73), but the issue persists in that branch as well

What this does

1. Introduces an integration test that simulates the failure condition of the form linked above. I downloaded the JSON from form.io and turned that into a test fixture, then wrote a very basic test that jumps to the third page, simulates clicking the "next" button, and checks that all of the required fields are properly marked as invalid.

2. Removes blue background from radio, checkbox, and fieldset components; preserves it in address and "well" components; and normalizes vertical spacing within nested components.

Review links

	v6.3.0	This PR
The broken form	Before	After
Fieldset component	Before	After
Well component	Before	After
Radio component	Before	After
Selectboxes component	Before	After
Address component	Before	After
Kitchen sink example	Before	After

The plan moving forward

1. Release this in #122
2. Deprecate 6.32. Cherry-pick the integration test onto the 7.0 release branch (and make sure that the test fails as expected!)
3. Get the tests passing again
4. Release 7.0 #73

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[shawnbot]

Closing as I've merged this manually in #122.