Allow find_in_batches to use :order, :limit, and :offset

Created patch which allows find_batches to use :order, :limit, and :offset for better control over batch processing. Also supports models which don't use integer primary keys.

See my reply on the main thread about why giving such options might not be a good idea.

Anyway, the will_paginate plugin provides the paginated_each class method on models which lets you iterate with :order and :per_page parameters.