Behat scenarios
PromotionBundle : fixing bug on non existent "equal" configuration
PromotionBundle : fixing bug (usage limit was not checked)
Rendering percentage discount ONLY on the items total (on not the whole order total)
Promotion coupon integration
Cleaning and refactoring Behat tests
Removing coupon handler and using CodeToCoupon form
Dispatching events related to coupons
Fixing CS and glitches
Handling flash messages related to coupons thanks to SyliusPromotionsEvents.
Fixing CS
Fixing specs and CS, cleaning code and tests cleaning after reviews
Merge pull request #429 from jjanvier/feature/coupons-integration

[WIP] Integrate the promotion coupons