List all notebook names in the notebook dir and path.

def get_notebook_names(self, path=''):
        """List all notebook names in the notebook dir and path."""
        path = path.strip('/')
        spec = {'path': path,
                'type': 'notebook'}
        fields = {'name': 1}
        notebooks = list(self._connect_collection(self.notebook_collection).find(spec,fields))
        names = [n['name'] for n in notebooks]
        return names