Bug：添加链接时似乎不支持包含中文的url

如：http://sitename.com/中文/

提示如下：
POST /project/tx/links/new (96.44.184.181)
Traceback (most recent call last):
File "/usr/lib/python2.6/site-packages/tornado-2.1.1-py2.6.egg/tornado/web.py", line 954, in _execute
getattr(self, self.request.method.lower())(*args, **kwargs)
File "/www/workspace/workspace/security.py", line 44, in wrapper
return method(self, *args, **kwargs)
File "/www/workspace/workspace/handlers/desktop/project/links/__init__.py", line 96, in post
link_url_sha1 = unicode(hashlib.sha1(link_url).hexdigest())
UnicodeEncodeError: 'ascii' codec can't encode characters in position 33-35: ordinal not in range(128)

这样比较不方便。