+act #3579 Direct ActorSelection for missing actor to deadLetters
=act Log random seed in case of SupervisorHierarchySpec failure

* It will never be deterministic, but with reproducble random sequence we
  might have a better chance to repeat run the test to reproduce failure.
=zer #3512 Harden zeromq ConcurrentSocketActorSpec

* 3 sec timeout waiting for terminated increased to 5 sec,
  ConcurrentSocketActor postStop (poller.unregister or socket.close)
  might perhaps take a while
* message from previous test step interleaved with next step, use
  separate endpoints for each step
!per #3707 Channel enhancements

- Persistent channel
- ConfirmablePersistent message type delivered by channel
- Sender resolution performance improvements
   * unstash() instead of unstashAll()

These enhancements required the following changes

- Unified implementation of processor stash and user stash
- Persistence message plugin API separated from implementation
- Physical deletion of messages
Merge pull request #1827 from krasserm/wip-3707-channel-enhancements

!per #3707 Channel enhancements
Merge pull request #1822 from akka/wip-3579-ActorSelection-deadLetters-patriknw

+act #3579 Direct ActorSelection for missing actor to deadLetters
=act #3507 Change format of ActorSelection.toString
Merge pull request #1823 from akka/wip-3507-ActorSelection-toString-patriknw

=act #3507 Change format of ActorSelection.toString
+act #3073 Add forward to ActorSelection
Merge pull request #1824 from akka/wip-3543-ActorSelection-forward-patriknw

+act #3073 Add forward to ActorSelection
=act #3590 Reject task scheduled too far in the future
Merge pull request #1831 from akka/wip-3590-refuse-tick-overflow-patriknw

=act #3590 Reject task scheduled too far in the future
Merge pull request #1834 from akka/wip-SupervisorHierarchySpec-patriknw

=act Log random seed in case of SupervisorHierarchySpec failure
Merge pull request #1836 from akka/wip-3512-zeromq-test-patriknw

=zer #3512 Harden zeromq ConcurrentSocketActorSpec
=doc Add dependency and sample to osgi docs
Merge pull request #1837 from akka/wip-3687-osgi-dependency-doc-patriknw

=doc Add dependency and sample to osgi docs
Merge remote-tracking branch: upstream/master