Fix registration problem

In the current version when I run on localhost and try to create a user, the web page says unexpected error and the console log says:
ERROR    2013-06-20 19:09:14,516 handlers.py:852] Unexpected error creating the user g: 'NoneType' object has no attribute 'activated'

This implements the fix described by alexsms on
https://github.com/coto/gae-boilerplate/issues/236#issuecomment-16306657

All unit tests pass