Improvements

Support for clustering using AWS EC2 Autoscaling Groups
Support for clustering using AWS EC2 Tags
Optional Cluster Cleanup feature that will remove nodes from a cluster if they are no longer visible to both RabbitMQ and the service discovery backend.
Optionally shutdown RabbitMQ if it can not join a cluster via the Failure Mode setting. Initial implementation by Giri-Chintala.
Consul Backend Improvements include:
- Added optional Consul behavior allowing for registration against a single Consul server/agent. Contributions by AlexeyRaga, Greg Durham, and Vitaly Aminev.
- Optional "auto-address" mode when registering against a single Consul server/agent
New Startup Delay setting causes RabbitMQ to randomly delay as an attempt to help race conditions when creating a brand new cluster.
Documentation cleanup and move to the GitHub project Wiki

Behavioral Changes

The default backend type of Consul was removed. You must now explicitly configure the backend type.
All Consul Service settings/environment variables were renamed/shorted. See documentation for details on the new keys/environment variables.
The plugin now requires the installation of the rabbitmq-aws plugin, even if you do not intend to use the AWS functionality.
The plugin now requires Erlang 17.5 or newer.

Fix Consul ACL tokens support - Andrei Skopenko
Strip out leading slashes in etcd keys, if they exist (#21) - Paul Becotte
Fix the DNS backend nodelist() function (#22) - Adam Romanek
Fix unregister for etcd (#32) - Chris Heng
When building the node list, use local part prefix of RABBITMQ_NODENAME for constructing the expected node names for other nodes in a cluster. (#56)