修正删除回帖无法没有更新回帖统计的bug

操作：添加
文件：/backstage.py

BackstageRemoveReplyHandler类

在“memcache.delete('Topic_' + str(topic.num))”上一行添加：
q3 = db.GqlQuery('SELECT * FROM Counter WHERE name = :1', 'reply.total')
if q3.count() == 1:
counter = q3[0]
counter.value = counter.value - 1
counter.put()

注意代码缩进