fix setup.py. close #324

setup.py

 # -*- coding: utf-8 -*-
+import io
+
 from setuptools import setup, find_packages
 
 
@@ -6,8 +8,8 @@ setup(
     name='django-pipeline',
     version='1.3.22',
     description='Pipeline is an asset packaging library for Django.',
-    long_description=open('README.rst').read() + '\n\n' +
-        open('HISTORY.rst').read(),
+    long_description=io.open('README.rst', encoding='utf-8').read() + '\n\n' +
+        io.open('HISTORY.rst', encoding='utf-8').read(),
     author='Timothée Peignier',
     author_email='timothee.peignier@tryphon.org',
     url='https://github.com/cyberdelia/django-pipeline',