1080p migration tweak

* Add some logging to each 1080p migration part so people see some sort of progress in their console
* Use show_id instead of tvdb_id for first part of migration, just in case there is a duplicate id or if show is missing tvdbid (never know)
* Optimize query by reducing the arithmetic performed each time and queuing the list of updates to perform using a transaction (thanks @Prinz23)