Refactor raw Sass

You'd never have a .visualisation that wasn't inside #content. I
don't think.
Don't display the colour bar on the raw page
Hide table-toggle element on raw page

This includes the child elements:

- The toggle link
- The actual table
Hide all nav elements on raw page

They're used for navigation, which is a bit useless in a PNG.
Merge pull request #263 from alphagov/66964496-data-table-toggle-png-fallback

Hide data table toggle link in PNG fallback