Fix typo in NodeNotFound exception

Signed-off-by: martin f. krafft <madduck@madduck.net>
diff --git a/reclass/errors.py b/reclass/errors.py
index 53f340a..dbd6a78 100644
--- a/reclass/errors.py
+++ b/reclass/errors.py
@@ -47,9 +47,9 @@
 
 class NodeNotFound(NotFoundError):
 
-    def __init__(self, storage, classname, uri):
+    def __init__(self, storage, nodename, uri):
         self._storage = storage
-        self._name = classname
+        self._name = nodename
         self._uri = uri
         msg = "Node '{0}' not found under {1}://{2}".format(self._name,
                                                             self._storage,