Connection retries to shutdown node, see #3326

* In EC2 connection time out is around 1 minute. A few messages
  were sent after quarantining and these caused endless restarts,
  and connect attempts with 1 minute interval.
* This change makes sure that the endpoint is stopped after the first
  failed connection attempt.
* Changed default settings for netty connection-timeout, and matching
  retry window to allow for 3 restarts
Forward port of release and build changes from 2.1
Merge pull request #1424 from akka/wip-3326-connection-retries-patriknw

Connection retries to shutdown node, see #3326
Compression of large cluster messages, see #3355
make release script really clean out the working directory
fix release printed in docs header
Merge pull request #1438 from drewhk/wip-release-script-updates-drewhk

Forward port of release and build changes from 2.1
Merge pull request #1440 from akka/wip-zip-patriknw

Compression of large cluster messages, see #3355
Merge pull request #1439 from akka/wip-release-script-∂π

forward-port the things we learned on the release-2.1 branch
 #3340 - Adding support for 0ms push timeout for blocking mailboxes
Shutdown ordering issue in RemoteDeploymentDeathWatchSpec, see #3334
Remove some unnecessary object creation and switch to HashSet for better performance. See #3308
Hardening of cluster member leaving path, see #3309

* Removed leader commands for Shutdown and Exit
* Member shutdown itself  when it sees itself as Exiting
* Singleton cluster with status Exiting will shutdown itself,
  in case the Exiting gossip never arrives
* Exiting member not part convergence check
* Exiting member is removed by leader (on convergence) when the
  exiting member is in the unreachable set, i.e. sucessfully shutdown
* Reverted the change made for #3266, i.e. Exiting is
  detected as unreachable again.
* Adjust ClusterSingletonManager to new Exiting behaviour
* Fix bug in HeartbeatSender, which caused it to continue to
  send heartbeats to removed nodes, instead of rebalancing
* Refactoring of leaderActions method
* Leaving section in docs
Merge pull request #1441 from akka/wip-3308-actorsystemspec-times-out-ban

ActorSystemSpec timeout fixes #3308
Change defaults for Netty pools, see #3346

server-socket-worker-pool.pool-size-max = 2
client-socket-worker-pool.pool-size-max = 2
Netty 3.6.6, see #3356
Use a dilated timeout for ConcurrentActivationTest. See #3269
Remove auto-join config, derive from seed-nodes, see #3359
Merge pull request #1432 from akka/wip-3309-exiting-patriknw

Hardening of cluster member leaving path, see #3309
Merge pull request #1443 from akka/wip-3359-auto-join-patriknw

Remove auto-join config, derive from seed-nodes, see #3359