Retrieve the API params from the config file.

def _get_api_params(api_url=None,
                    page_id=None,
                    api_key=None,
                    api_version=None):
    '''
    Retrieve the API params from the config file.
    '''
    statuspage_cfg = __salt__['config.get']('statuspage')
    if not statuspage_cfg:
        statuspage_cfg = {}
    return {
        'api_url': api_url or statuspage_cfg.get('api_url') or BASE_URL,  # optional
        'api_page_id': page_id or statuspage_cfg.get('page_id'),  # mandatory
        'api_key': api_key or statuspage_cfg.get('api_key'),  # mandatory
        'api_version': api_version or statuspage_cfg.get('api_version') or DEFAULT_VERSION
    }