pagination work
- Added multiple variants to the product updater service spec
 - Moved the productchange service to spree
- Added the frontend for displayable variants
- Take into account a taxons ancestors ( parents ) when add a taxon to a product
- fixed a bug where you can not deselect all the variants
-added method to find uniq displayable variants
Product Update Service only create new displayable variant for selected variants
- Tidy up the displayable variants view and add select all button
visible option_type core and product update service
Variant Display name show option value when configured to do so
- updated the awesome nested set