Repos are generally better since otherwise we end up duplicating
things between front-end and API.
Types moved to by CONST values within a class for better visibilty
of usage and listing of types.
- Tweaked how books are passed on update to prevent unassignment if
parameter is not provided.
- Added books to validation so they show in docs.
- Added request/response examples.
- Added tests to cover.
- Added child book info to shelf info.
Review of #1908
API listing endpoint filter can be found via &filter[name]=my+book query
parameters. There are a range of operators that can be used such as
&filter[id:gte]=4
