Registers the filepath for an rml mapping

        Args:
        -----
            filepath: the path the rml file

def register_rml(self, filepath, **kwargs):
        """
        Registers the filepath for an rml mapping

        Args:
        -----
            filepath: the path the rml file
        """
        name = os.path.split(filepath)[-1]
        if name in self.rml_maps and self.rml_maps[name] != filepath:
            raise Exception("RML name already registered. Filenames must be "
                            "unique.",
                            (self.rml_maps[name], filepath))
        self.rml_maps[name] = filepath