Test permission system integrations

[ljacqu]

It would be nice to somehow have a way to test our hooks into permission systems. I could imagine a few solutions:

• as unit tests, if possible at all (I can imagine that it's hard to initialize other plugins as to check the interactions with them. Otherwise writing unit tests won't really test much.)
• Some command that will generate a few test users with different permissions. The question here is if we need to keep a permissions file for each plugin system...