=tes #3727 Fix timing failure in TestTimeSpec
=pro Upgrade to sbt 0.13.1
=doc #3792 Fixed broken tex/pdf config
Merge pull request #1889 from akka/wip-upgrade-to-sbt-13.1-ban

=pro Upgrade to sbt 0.13.1
Merge pull request #1892 from akka/wip-3792-sphinx-pdf-generation-failed-ban

=doc #3792 Fixed broken tex/pdf config
+con #3758 Provide sharding of actors in a cluster

* Delete files only from controller
* Change default retry settings of singleton to speedup startup
* Persistent snapshots
Merge pull request #1843 from akka/wip-cluster-persistence-patriknw

+con #3758 Provide sharding of actors in a cluster
Merge pull request #1882 from akka/wip-3727-TestTimeSpec-patriknw

=tes #3727 Fix timing failure in TestTimeSpec
=rem #3726 Fix race in RemoteWatcher for first quick watch/unwatch

* The problem scenario was that a remote watch followed by re-watch triggered by
  first heartbeat and unwatch coming in before the extra re-watch message. That
  caused RemoteWatcher to still watch the subject even though it was intended to
  be unwatched.
* I could reproduce it with sleeps at stratgic points
* Sovled by separate re-watch message and check that still watching
Merge pull request #1866 from akka/wip-3726-remote-watch-cleanup-failure-patriknw

=rem #3726 Fix race in RemoteWatcher for first quick watch/unwatch
Merge remote-tracking branch: upstream/master