关闭jieba结巴分词日志输出

使用结巴分词，会输出如下日志：

Building prefix dict from /usr/lib/python2.7/site-packages/jieba/dict.txt ...
Loading model from cache /tmp/jieba.cache
Loading model cost 0.182227134705 seconds.
Prefix dict has been built succesfully.      

logging日志级别（5个等级），从低到高分别是：

DEBUG
INFO
WARNING
ERROR
CRITICAL      

不显示debug信息，只要大于 logging.DEBUG 级别即可，比如：

import logging

jieba.setLogLevel(logging.INFO)      

参考：

jieba如何关闭stderr的日志 #255