Get user docker configuration

    Return: dict

def _get_config():
    '''
    Get user docker configuration

    Return: dict
    '''
    cfg = os.path.expanduser('~/.dockercfg')
    try:
        fic = open(cfg)
        try:
            config = json.loads(fic.read())
        finally:
            fic.close()
    except Exception:
        config = {'rootPath': '/dev/null'}
    if not 'Configs' in config:
        config['Configs'] = {}
    return config