Clean up dead user accounts after some time
This is the current behaviour:
- create a test account
- destroy it (logged into the webapp)
- signup with the same name -> "has already been taken"
I think this is meaningful because it prevents people from taking over other peoples user account after it has been removed. If they did they'd have a chance of receiving email that was not meant for them for example.
However we want to free the namespace after some time. So we need to clean up outdated useraccounts from time to time.
(from redmine: created on 2013-09-13)