Flows no longer need to be saved between uses.

Also introduces util.positional declarations.

Reviewed in http://codereview.appspot.com/6441056/.

Fixes issue #136.
diff --git a/samples/tasks_appengine/app.yaml b/samples/tasks_appengine/app.yaml
index 35a7dc6..27372f7 100644
--- a/samples/tasks_appengine/app.yaml
+++ b/samples/tasks_appengine/app.yaml
@@ -4,9 +4,8 @@
 api_version: 1
 
 handlers:
-- url: /oauth2callback
-  script: oauth2client/appengine.py
 - url: /css
   static_dir: css
+
 - url: .*
   script: main.py