Allow inventory tracking control (enable/disable) at the variant level. This retains the site-wide inventory tracking flag, but also allows this type of control down at the variant level.
NEMO-545 minor fixes and additional unit tests for inventory tracking updates
Merge branch '2-0-stable' of github.com:spree/spree into inventory_by_variant_pr
add order_inventory support for inventory tracking at variant level
Merge branch 'inventory_by_variant_pr' of github.com:godaddy/spree into 2-0-stable