Not handling switch reconnect and disconnect correctly

When a switch disconnects and reconnects, we are not handling the sync of configuration correctly.

A correct handling would involve a mark and sweep to bring the switch into sync with the controller. We do not have time to do this correctly.

A workable solution is:

1) On switch disconnect, in plugin, remove all of the flow, group, and meter for the node from the configuration tree.
a) This can be done either by removing the FlowCabableNode Augmentation from the node or by removing all the Tables,Groups, and Meters. It should not be done by removing the Node.
b) In the FlowTransaction, we will need to wrapper the call to the removeFlow RPC to catch the exception if the node is not services by a working switch.
2) On switch connect, in the plugin, send a message to the switch deleting all Flows, Groups, and Meters prior to the initial poll for stats (I'd recommend a barrier on this).