+act #3592 Read stash-capacity from mailbox config
=doc #3596 Add paragraph about Agent locality

* Based on discussion on akka-user, Sept 6-9 2013. It seems appropriate
to mention that Agents are not remoteable, so that naive users (like me)
know to design for that.
* This change has not been locally built with Sphinx, but seems to be
small and safe.
=pro #3569 Remove experimental label from cluster pom.xml
!clu #2307 Allow transition from unreachable to reachable

* Replace unreachable Set with Reachability table
* Unreachable members stay in member Set
* Downing a live member was moved it to the unreachable Set,
  and then removed from there by the leader. That will not
  work when flipping back to reachable, so a Down member must
  be detected as unreachable before beeing removed. Similar
  to Exiting. Member shuts down itself if it sees itself as
  Down.
* Flip back to reachable when failure detector monitors it as
  available again
* ReachableMember event
* Can't ignore gossip from aggregated unreachable (see SurviveNetworkInstabilitySpec)
* Make use of ReachableMember event in cluster router
* End heartbeat when acknowledged, EndHeartbeatAck
* Remove nr-of-end-heartbeats from conf
* Full reachability info in JMX cluster status
* Don't use interval after unreachable for AccrualFailureDetector history
* Add QuarantinedEvent to remoting, used for Reachability.Terminated
* Prune reachability table when all reachable
* Update documentation
* Performance testing and optimizations
Merge pull request #1701 from akka/wip-2307-reachable-patriknw

!clu #2307 Allow transition from unreachable to reachable
Merge pull request #1720 from jducoeur/master

=doc #3596 Add paragraph about Agent locality
Merge pull request #1713 from akka/wip-3592-stash-capacity-from-mailbox-conf-patriknw

+act #3592 Read stash-capacity from mailbox config
Merge pull request #1721 from akka/wip-3569-cluster-pom-experimental-patriknw

=pro #3569 Remove experimental label from cluster pom.xml
Merge remote-tracking branch: upstream/master