Push notifier

Push notifier lacked the ability of posting status changes. Some other issues were faced:
* Thread-safe job instantation delegating it to the JobStorage object.
* Eventbus is now asynchronous as many listeners perform heavy load opperations as db queries an http posts.
Note: XmlWriting should undergo through a refactoring process, JobXmlWritter is becoming bloaty to control which elements are included in the xml representation