Add on-hold inventory quantity for the Variant
Hold inventory
Release inventory
Reported fixes
Release inventory, take care about inventory quantity
Fixed specs
Update composer.json & dependencies of the project
Merge pull request #870 from stloyd/feature/composer_deps

Update composer.json & dependencies of the project
Move purchase step from PayumBundle into CoreBundle
Merge pull request #949 from stloyd/feature/move_step

Move purchase step from PayumBundle into CoreBundle
Return to payment step if payment failed.
Add translation message.
Add event.
Implemented PurchaseListener
Merge pull request #817 from kayue/feature/failure-payment-flow

Return to payment step if payment failed.
PurchaseListener C fix
Merge pull request #938 from umpirsky/feature/on-hold-inventory

Add on-hold inventory quantity
On hold inventory status fixes
Merge pull request #952 from umpirsky/fix/on-hold-inventory

Fix/on hold inventory
Change properties' visibility to protected.