Add latest version of ujson

Author: goanpeca

setup.py

@@ -34,7 +34,7 @@
     install_requires=[
         'future>=0.14.0; python_version<"3"',
         'futures; python_version<"3.2"',
-        'ujson<=1.35; platform_system!="Windows"',
+        'ujson>=2',
     ],
 
     # List additional groups of dependencies here (e.g. development