Tariff moved to Point in Time DB architecture.

This adds oplog tables for TARIC tables and reconstructs current state
with the help of DB views. It enables us to rollback to any point time
backwards.

This enables TARIC validations that we have currently in place. The
validation framework was rewritten to have reasonable record error
messages.

TARIC importer got upgrade in relation with enabled validations. It also
uses less memory due to reduced usage of Nokogiri (uses hashes for
record parsing now).
Remove empty concern.
Missing migration, bad merge
Move data migration to later date

Since changes to oplog structure were made in parallel this migration
tries to run its query on view tables and fails. We have to apply to
oplog table.
Fix Measure conformance validations

Fixes ME6, ME13, ME14 to support meursing additional codes
Remove db/schema.rb

Sequel does not yet support view creation in schema file.
Add note about schema.rb to README.
Remove TODO note.

This is handled by ME8 conformance validation.
Remove TODO, this was implemented.
Use maintained version of sequel-rails.
Do not dump schema in SQL until it is implemented for MySQL.
Remove outdated comment.
Refactor default attribute processing for TARIC records.
Remove mocha dependency

Use plain rspec + rspec-spies. Mocha causes too much problems and issues
too many warnings.
Add ability to rollback oplog tables to certain date
Added ability to force redownload when doing rollback

Just removes the update entries instead of marking them as pending
Lock sequel-rails