[CartBundle] Fixed event used in CartListener and added specs

The dispatched event is CartItemEvent instead of CartEvent, it uses the getItem method only available in CartItemEvent
Fix - CMF Page doesn't work (missing template)
[ResourceBundle] Reduce dependency on Twig extension
Merge pull request #1576 from stloyd/feature/reduce_twig_deps

[ResourceBundle] Try to reduce dependencies in Twig extension
[CoreBundle] Use REST handling in ProductController
Creating unnamed form for api request and PATH support
Merge pull request #1578 from stloyd/bugfix/use_rest

[CoreBundle] Use REST handling in ProductController
Merge pull request #1569 from franmomu/cart_listener_and_specs

[CartBundle] Fixed event used in CartListener and added specs
Merge pull request #1575 from aRn0D/resource-post-method

Creating unnamed form for api request and PATH support
It fixes an exception while checkout in finite.

Exception message was "The "create" transition can not be applied to the "pending" state of object "Sylius\Component\Core\Model\Order" with graph "sylius_order"
add flash message for payment with state new.
[payum] set payment entity as a model, correctly pass details back to payment entity.
revert hacky fix.
[finite][payment] add way from new state to failed.
Merge pull request #1573 from antonioperic/master

Fix - CMF Page doesn't work (missing template)
Extract promotion subject interfaces
Implement new interfaces in core
Configurable item based promotions parameter
Item based in test env
Fix tests