* update copy to handle pluralisation in the case of joint purchase for previous ownership, with associated testing changes
* update copy to handle pluralisation in the case of joint purchase for staircasing, with associated testing changes
* update copy to handle pluralisation in the case of joint purchase for buyer previous, with associated testing changes
* make minor linting changes and update the evil test about number of pages
* potential variation on how to achieve pluralisation
* use built in rails methods of pluralising copy