python 时间处理
https://blog.csdn.net/xiaobing_blog/article/details/12591917
字符串日期向前向后1天
if kwargs.has_key('sday__lte'):
ltedate = datetime.datetime.strptime(kwargs['sday__lte'],'%Y-%m-%d')+datetime.timedelta(days=1)
kwargs['sday__lte'] = ltedate