fixed bug in welcome and added more examples

applications/welcome/models/db.py

@@ -44,7 +44,7 @@ auth = Auth(db, hmac_key=Auth.get_or_create_key())
 crud, service, plugins = Crud(db), Service(), PluginManager()
 
 ## create all tables needed by auth if not custom tables
-auth.define_tables()
+auth.define_tables(username=False, signature=False)
 
 ## configure email
 mail=auth.settings.mailer
@@ -79,3 +79,5 @@ use_janrain(auth,filename='private/janrain.key')
 ## >>> for row in rows: print row.id, row.myfield
 #########################################################################
 
+## after defining tables, uncomment below to enable auditing
+# auth.enable_record_versioning(db)