Update to attachment point flapping logic.  Use active time instead of last seen to order the entities.  Corresponding changes to unit tests.

Add some additional unit tests and change error status to null from NONE.  Some minor serializer cleanup

Correct race condition in device learning and topology, remove deviceManager from listening linkEvent

This reverts commit 0ae432f4.

Conflicts:

	src/main/java/net/floodlightcontroller/devicemanager/internal/DeviceManagerImpl.java

Cleanup of topology manager to match floodlight style.  Remove StackTraceUtil.  Add packet-in listener to topology

This reverts commit 51ca40a3.

Conflicts:

	src/main/java/net/floodlightcontroller/devicemanager/internal/DeviceManagerImpl.java