Only delete user-specific data on logout

[bjrne]

We don't really nee to delete courses for example, enrollments should be enough. This would lead to a much better user experience as reloading and parsing the course page on openSAP might as well take 15-20 seconds.

Subtasks:

• [ ] Think about all entities that can stay
• [ ] Verify that all delete-rules are appropriate
• [ ] Adapt the clearCoreDataStorage method

[janrenz]

based on your user you have permissions to see different courses. so not deleting them could lead to people seeing courses they dont have a permission to see

[bjrne]

oh right :/

[bjrne]

This is obsolete now, right @mathebox?

[mathebox]

Yes.