Return the actual column instance instead of just the name
If order should be reversed, read the `order_by_column` defined clustering order and reverse it instead of always using `:desc`
Allow use of host IP from environment variable
Mind the `order_by_column` clustering order when fetching in batches
Set `order` to `:desc` on `PublishedPost` model to be able to properly test the `#reverse` method; test examples impacted by this change are adapted (reversed expected results); now using `PublishedPost` instead of `Post` for the `#reverse` examples.
Add `sort_direction` method to DataSetBuilder
Define RecordSet#ascends_by? and #descends_by?

Use these to determine sort column order and to figure out which direction to
go in batches