BUG 2049  DataStore failure in StatisticsManager
BUG 2101  When L2 switch installed, its flows are interpreted as new flows with each stats request

* hashCode is not safe in general so we'd like to prevent Collisions how we can
	* we change HashBuilding to KeyBuilding from toString method
		* toString is generated in CompileTime
		* it can not be change during JVM run
		* every one use same YANG model version and jar files
		* and the same aproach could by use across claster
* add cleaning disconnected Node from StatListeningCommiter implementers

Change-Id: I645e9f07382af0b293bc43698446b7b84b95bbde
Signed-off-by: Vaclav Demcak <vdemcak@cisco.com>
Merge "BUG 2049  DataStore failure in StatisticsManager BUG 2101  When L2 switch installed, its flows are interpreted as new flows with each stats request"