Add a flag to handle RabbitMQ high availability

A combination of durable queues and classic queue mirroring can be used
to provide high availability of RabbitMQ. However, these options should
only be used together, otherwise the system will become unstable. Using
the flag ``om_enable_rabbitmq_high_availability`` will either enable
both options at once, or neither of them.

There are some queues that should not be mirrored:
* ``reply`` queues (these have a single consumer and TTL policy)
* ``fanout`` queues (these have a TTL policy)
* ``amq`` queues (these are auto-delete queues, with a single consumer)
An exclusionary pattern is used in the classic mirroring policy. This
pattern is ``^(?!(amq\\.)|(.*_fanout_)|(reply_)).*``

Change-Id: I51c8023b260eb40b2eaa91bd276b46890c215c25