Fixes for item change monitoring in ODID MediaServer

Removed the monitoring of item files separately from the item
 directory in HarvestingTask. Directory monitoring issues seemed to be
 related to an older version of the Ubuntu kernel () (in my case, going from
 3.2.0-36-generic-pae #57-Ubuntu SMP to 3.2.0-58-generic-pae #88)

With the kernel upgrade, the item touch logic in the ODIDMediaEngine stopped
 signaling FileMonitorEvent.CHANGES_DONE_HINT for some unknown reason. So
 added FileMonitorEvent.ATTRIBUTE_CHANGED to the list of events in the
 Harvester that will done generate the_on_changes() signal. Cases where
 both are signaled are handled upstream.

Performed tests with both the MediaEngine-induced change and "touch"
 (both Doug and I). Seems to be working reliably.