Adding an elaborate description of the API.
1. Added @login_required to api_page
2. Now passing api_base and user_uri to the template. api_base has the full URI of the base api endpoint. User_uri is the relative uri for the current user.
Added documentation about PATCH and DELETE.
Now most of the page (sorting buttons, list of items) are only displayed if request.user.is_authenticated().
Now the navigation (that is, the link to the API page) is only displayed if request.user.is_authenticated().