Update Packetcable project to replace DataChangeListener (deprecated) with DataTreeChangeListener

OpenDaylight has decided to deprecate and subsequently remove the DataChangeListener class with DataTreeChangeListener/ According to Alexis De Talhouet, the DCL class will remain in deprecated in OpenDaylight through the Carbon release. DCL will be removed subsequent to Carbon. The Packetcable project uses DCL so it would be a good idea to restructure our code to make the migration before Carbon is released.

Alexis provided an example to guide rework of our code:

https://github.com/opendaylight/unimgr/blob/master/impl/src/main/java/org/opendaylight/unimgr/api/UnimgrDataTreeChangeListener.java