fix: Database version management
fix: Database version management

The migrate_version database was being initialized to the wrong
value. The upgrade mechanism was also messy, as the new version
had to be entered to multiple places. Fixed and clarified.

aalto-trafficsense/regular-routes-server,aalto-trafficsense/regular-routes-server,aalto-trafficsense/regular-routes-server,aalto-trafficsense/regular-routes-server