Fix collapsibleness

It seems that since the HMRC Manuals API switched to providing a `document.body` (which was only being used before for collapsible manual content) these pages are being rendered as collapsible when they shouldn't be. 

This PR re shuffles the HMRC and non HMRC HTML so that the HMRC manuals are not collapsible.

There are two pieces of further work for this, one is to remove some more of the collapsible HTML into the javascript so it isn't cluttering up the view, and the other is to add back in a thrid-width style for the HTML which the javascript then removes when it loads and adds only to the body-content.