Testing the importer without transactions

The transaction was too large, and should an import fail
the only option is to rollback the db anyway, this can be achieved via
the rollbacks api.

Testing the import process without transactions to see if it helps
Redis related cleanup for test suite
Change dates in integration specs
Merge branch 'fixing_slow_tests' into remove-transactions
Fix specs related to transactions
Merge pull request #185 from bitzesty/remove-transactions

Remove transactions from the importer
Set defaults for rollback to delete records. Add columns that hold error stacktraces
Fix rollback table.

According to the latest changes in rollback script.
README update
Use correct dates during rollback
Fix rollback related specs

Conflicts:
	spec/integration/tariff_synchronizer_spec.rb