Tariff synchronizer enhancements

This change is for https://www.pivotaltracker.com/story/show/59042540

* Makes synchronizer check for updates continuously throughout the day in case two TARIC updates will be added at different times
* Adds last 10 issued SQL commands to exception email for easier debugging
* When update/destroy operation fails due to record not being found in `TaricImporter` we will now be seeing `Sequel::RecordNotFound` exception instead of no method on `nil` which is a consequence of record not being found.