Styling Frontend for other Manuals

Also making the static text specific to HMRC happen if required and
adding the topics and organisations to the header.
Adding ManualPresenter

Some of the information tied to the DocumentPresenter didn't really make
sense there, so I've extracted it out to a ManualPresenter and used that
in the views where relevant.
Using a repository to fetch the manual

As we move to using the content_api, the App will use this repository to
fetch the manuals and their sections.