Bug 1484 - StatisticManager performance improvement refactoring

* migration to new MD-SAL API (DataBroker DataChangeListener)
* splitting project api/impl + (javaDoc for api)
* clean pom.xml (xtend dependency and private-package, add sal-binding-broker-impl for test)
* chaining req/resp StatisticNotification per FlowNode per statistic for prevent DS and RPC queue overload
* add multipart msg joiner (StatManager wait for all relevant multipart msg for notification before write relevant
	Oper/DS action) - possibility to remove all not used subtrees (target -> reflect actual device contain asap for
	all alien node's data).
* add FlowNode registratration - registration needs all SwitchFuture information for make a correct Stat target list (flows,
	groups, meters, queues, tables, nrOfTables, ports) - fix for sending not supported notifications to device
* add logic for unique identification FlowId - DeviceFlow (create unique tweens FlowId and flowHash from responded device
	flow fields like match, priority, flowCookie, flowCookieMask)
* change FlowCookieMap to FlowHashMap -> List<FlowHash, FlowId>
* implement parallel statistics collecting for FlowCapableNode Sets
* add MockTestSuite for a StatManager workflow interaction testing (neet to be fixed for newest changes)

PASS tests https://jenkins.opendaylight.org/integration/job/integration-master-csit-base-of13
PASS tests https://jenkins.opendaylight.org/integration/job/integration-master-csit-karaf-l2switch-only/
PASS tests https://jenkins.opendaylight.org/integration/job/integration-master-csit-karaf-compatible-min/

Change-Id: I265b57378fc19573d6f18036825cb57f4131ca80
Signed-off-by: Jan Hajnar <jhajnar@cisco.com>
Signed-off-by: Vaclav Demcak <vdemcak@cisco.com>