No transaction-handling

[chland]

Right now, the library isn't using transaction-handling. IMHO it would be a good idea to add it to all functions where multiple updates/deletes are executed to prevent any problems if the db-server dies halfway through deleting stuff. For example in delete_user(), delete_group() or delete_perm(), multiple delete-queries are executed.

I started to add some basic transaction-handling to the code and can create a PR from my changes later today when i'm done.

[REJack]

That's a great idea and your changes looks good and works.

[REJack]

Issue closed