Do not overwrite category if external event is imported
Do not overwrite category if external event is imported

This is an ugly hack to fix the issue with all changes to facebook events (except age limit and price) being overwritten every day, resulting in a lot of events with the OTHER category. We should handle events differently based on where they come from.

Resolves #91

Studentmediene/Barteguiden,Studentmediene/Barteguiden