CRUD promises

Most operations in the DAP are executed through promises. It means that they are queued for execution and the real execution occurs asynchronously. This is the case of CREATEs, UPDATEs and DELETEs of things coming from the Activity's Execution Engine. In case of errors in the execution of queued promises, this error is reported through the /sensor_network/promise_feedback topic in the form of an observation. Under this topic there will be a subtopic for the thing type and inside it and subtopic for the thing ID. For instance, the result of a CRUD operation over the thing truckInstance of type truck will be reported under /sensor_network/promise_feedback/truck/truckInstance.