sync version with mapnik core

Author: artemp

setup.py

@@ -253,7 +253,7 @@ def run(self):
 
 setup(
     name="mapnik",
-    version="0.1",
+    version="3.1.0",
     packages=['mapnik','mapnik.printing'],
     author="Blake Thompson",
     author_email="flippmoke@gmail.com",