Duplicate log events for Workflow

Since a2eaa8f46096, specific actions are logged.

We noticed a problem with the log of Workflow on a sale. As the Workflow decorator is declared each time a module update a transition, then the log on this transition is written many times.

For instance, the transition "quote" on sales is called in sale but also in : sale_promotion, sale_shipment_cost, sale_opportunity, sale_stock_quantity, commission, sale_blanket_agreement, sale_advance_payment, sale_gift_card and sale_extra. So if all those modules are activated, once you will do the quote transition on sale, you'll have 10 lines of the same log at the same time: "Transitionned to - State: Quotation".