Prepare Lippupiste importer for use without Toimipisterekisteri

[aleksisalonen]

Current version of the Lippupiste data importer works only when paired with Toimipisterekisteri. Location data from Lippupiste is always matched to Toimipisterekisteri registry.

Functionalities should be added in location matching for 1) sniffing around for matches in all data sources' location data 2) adding new locations to Linked Events when no corresponding location is found.

Improvement is intended to widen the applicability of the importer to LE-instances outside Helsinki.