Bug 423516 - Rules of type "System started" should start after Item Initalization

 * Refactored FolderObserver service in such a way to use the WatchService java system
 * Modified FolderObserver configuration and moved to the services directory

Please check if are ok for you, and then I'll create the abstraction system of ESH WatchServices and they will adapt ConfigDispatcher and FolderObserver services. 

I preferred to separate the work because the refactoring of ConfigDispatcher implicates different bundles and requires time.

Signed-off-by: Fabio Marini <fabio.mariniss@gmail.com>
This call throws a java.nio.file.ClosedWatchServiceException in case the watch service has been closed (what happens if there there is a configuration update.