aur-dev: improvements

Our current aur-dev instance has a few issues which make testing impossible:

• No dataset is available, previously we had a copy of the production database but this is an obvious no go. The AUR has a dummytest set creation script. This creates accounts and all with the same username/password.
• Live mail setup is active, which means it can be used to spam real emails or people testing
• Registration is enabled, so this test system can be actively (ab)used. The AUR has no way to disable registration, it can disable http logins.