[DPP-48] Atomic Broadcast / Guaranteed Multicast

[qnikst]

[Imported from JIRA. Reported by Tim Watson [Administrator] @hyperthunk) as DPP-48 on 2013-01-07 18:05:18]

See RabbitMQ's implementation and ZaB as reference architectures:

• http://wiki.apache.org/hadoop/ZooKeeper/Zab
• http://hg.rabbitmq.com/rabbitmq-server/file/default/src/gm.erl

[qnikst]

Duplicate #48