When an api endpoint only accepts POST requests, a dedicated view with
different url and name accepting GET requests has to be created in order
to display the HTML documentation.
Add a new parameter to the api_doc decorator to handle that special case.
- in order to simplify the use of the apidoc module, create a dedicated view to display HTML documentation for each decorated endpoint.
- the noargs parameter is still used but is no more mandatory to an endpoint without URL arguments. When set to True, it simply enables to avoid redirecting to the endpoint doc view from the endpoints list view as response data can be immediately displayed.