fix duplicate auth_token in development database images

This pull request fixes some bugs caused by duplicate auth_token in developer db images. `lookup_from_auth_token` selects the first user with an auth_token. One bug to reproduce is this:

1. import the database from development-image.sql
2. login as eviltrout:password
3. go to `/message-bus/_diagnostics`
4. you get "not allowed"

I think the best way is not to include any auth_token in the db dump, so it will be recreated at login.