Cleanup indexed data before recrawling dataset
- current implementation: delete all indexed data
- a more sophisticated solution could be set up later ->necessary?
(from redmine: issue id 966, created on 2018-02-09tgradl, closed on 2018-02-09)
(from redmine: issue id 966, created on 2018-02-09tgradl, closed on 2018-02-09)