Antidote channels

[balegas]

Replacement for inter-dc zeromq implementation.

Provides a library to abstract zeromq communication patterns from inter-dc replication code. Supports ZeroMQ and RabbitMQ and provides an extensible interface.

Current implementation was tested for ZeroMQ. Performance is comparable to current implementation. In the long-term we will want to use this library to test the performance of RabbitMQ against ZeroMQ, or to replace the underlying erlzmq library.

[FairPlayer4]

This will have to be updated significantly due to the changes in master I like the idea of having an alternative message queue service