def getPageConfig(pageIndex, retJson=True):
    """ Return layout config of specific page.

        @param pageIndex
        index of the page

        @retJson
        format return value to json format or not( default True )

        @return
        a dict contains page layout config, format like:
        {
            'success': True,
            'msg': 'Get page config success.'
            'config': {...}
        }

        """
