Automatization ConcertAnnouncement to Concert Algorithm

The bulk of the rule engine that cleans and deduplicates concert announcements is implemented here: https://github.com/Kunstenpunt/havelovewilltravel/blob/master/hlwtadmin/models.py#L706-L891 It is called in the .save() function of Model ConcertAnnouncement

The algorithm in pseudo-code:

pseude code