!per #3916 upgrade org.iq80.leveldb to 0.7
+con #3843 Add ClusterSingletonProxy
Merge pull request #2063 from agourlay/upgrade-leveldb

upgrade org.iq80.leveldb to 0.7
!dat #3920 Remove deprecated akka-dataflow
!tra #3920 Remove deprecated akka-transactor
!tra #3920 Remove deprecated durable mailboxes
!clu #3920 Remove deprecated Cluster.publishCurrentClusterState
!clu #3920 Remove deprecated akka.cluster.auto-down

* replaced by akka.cluster.auto-down-unreachable-after
!act,rem,clu #3920 Remove deprecated old routers
!act #3920 Remove Timeout constructor without unit
!rem #3920 Remove LogRemoteLifecycleEvents
!con #3920 Remove JavaLoggingEventHandler
!act #3920 Remove UntypedActorFactory
!tes #3920 Remove TestKit.dilated
Merge pull request #2066 from akka/wip-3920-remove-deprecated-patiknw

Remove deprecated features
Merge pull request #1977 from giovannibotta/master

#3843 Add ClusterSingletonProxy