try on coveralls
reordering siblings checkpoint
4.2.1!
make db-specific implementations (YUCK) for _ct_reorder_siblings
use _ct_reorder_siblings in append_sibling, remove fixture tests, and properly reorder siblings from prior parent
* implement _ct_reorder_siblings for postgres
* options[:order] is now order_by
* make numeric reordering to use sql updates
* fix issues that prevented sort order to stay 0..N when deletes or inserts happen
support rails 3.0 (which doesn't have update_column)