Add more tests

Just define the implementation a little.
Merge pull request #635 from alphagov/feature/register-to-vote-live

Feature/register to vote live
Merge pull request #634 from alphagov/add-more-url-formatting-tests

Add test which includes &
Fix register to vote digital take-up table

We were using the default axes, which referenced completion rate.
Merge pull request #639 from alphagov/register-to-vote-digital-takeup

Fix register to vote digital take-up table
Change module description to use a paragraph tag

I'm not sure this should be a heading, I think it's just body text.

Update the styles to match.
Switch module styles to be mobile first
Add right margin to the filtered list status text

This stops the 'x' to remove a filter from touching the text to
the right of it.
Update unpublished warning styles

With feedback from @henryhadlow.
Add prototype warning to page-per-thing