Release 1.2.2

A number of fixes in this release address issues arising from the akka upgrade
in 1.2.0.

Fixes

7574dfc Do not send out-of-order events to StateSupervisor
d28af99 prune dead members from memberAgents
2fcd04c add periodic state check for leader state
a770ea1 Return false for timed-out isOnline calls
e424df9 start a scout if remote leadership fails

Default configuration changes

7c6e757 Gate failed connections for 200ms
391e8a2 Adjust values to line up with 2.3 defaults
b547e8c Disable quarantining, dial back health sensitivity
3880065 Lessen default LeadershipPing interval

New Features

834c0fa De-stringify non-string config values
3ad2289 Introduce .getDouble and .getInt to SiriusConfig
232b7cd More precise downcast for .getProp
f6e2f1f Augment MembershipActor monitoring

Documentation

a529dfc Updated external documentation links.
8679d6e Fix external links in Scaladocs.
8a5c865 Add links for issues and questions.

Project Maintenance

4f43707 use bintray for dependency resolution
616900c Upgrade to sbt 0.13.2