Fixed issue with url assembly.

Author: victor73

osdf.py

@@ -181,7 +181,7 @@ def get_node_by_version(self, node_id, version):
 
         Returns the parsed form of the JSON document for the node
         """
-        osdf_response = self._request.get("/nodes/%s/ver/%s", (node_id, version))
+        osdf_response = self._request.get("/nodes/%s/ver/%s" % (node_id, version))
 
         if osdf_response["code"] != 200:
             headers = osdf_response['headers']