[setup.py] Do not use unicode literals

See http://bugs.python.org/issue13943 for context

setup.py

@@ -1,7 +1,7 @@
 #!/usr/bin/env python
 # -*- coding: utf-8 -*-
 
-from __future__ import print_function, unicode_literals
+from __future__ import print_function
 
 import pkg_resources
 import sys