Implements a OPTIONS HTTP method function returning all allowed HTTP
        methods.

def options(self, request, *args, **kwargs):
        """
        Implements a OPTIONS HTTP method function returning all allowed HTTP
        methods.
        """
        allow = []
        for method in self.http_method_names:
            if hasattr(self, method):
                allow.append(method.upper())
        r = self.render_to_response(None)
        r['Allow'] = ','.join(allow)
        return r