Docs whitespace fix.
Remove `filter_backend`.

Closes #1775.
Remove `allow_empty`.

Closes #1774.
Remove `allow_empty`
Remove `pk_url_field`, `slug_url_field`, `slug_field`.

Closes #1773.
Remove `page_size` argument.

`paginate_queryset` no longer takes an optional `page_size` argument.
Remove `.model` usage in tests.

Remove the shortcut `.model` view attribute usage from test cases.
Minor tidy up.
Remove deprecated generic views.

`MultipleObjectAPIView` and `SingleObjectAPIView` are no longer
required.
Remove `.link()` and `.action()` decorators.
`get_paginate_by` no longer takes optional `.queryset`
Remove unused imports.
First pass
Add relations and get tests running
Getting tests passing
More test passing
Workin on
More test sorting
Fleshing out serializer fields
Tweaks