BugFix : Changes to get ping between two hosts to work

BugFix : Changes to get ping between two hosts to work

1. InventoryUpdates were not getting to ConnectionManager because the InventoryAndReadAdapter was not tracking all listeners
2. DataPacketServiceAdapter was not setup as an IPluginInDataPacketService
3. DataPacketServiceAdapters delegate was not set to the PacketProcessingService
4. Node was not set on the TransmitPacketInput causing an NPE somewhere in the MD-SAL internals (this should probably be better addressed as I have hit this twice already)
5. DataPacketServiceAdapter now handles situation where the NodeConnectors is null

Current state
An IllegalArgumentException is being thrown from the openflowplugin "Session cookie is invalid" - Need to look at that further

Change-Id: I643ea435d7bda9ee7b3a5d603a381c3cfbaa0cce
Signed-off-by: Moiz Raja <moraja@cisco.com>