This change implements and enables by default quorum support
for rabbitmq as well as providing default variables to globally tune
it's behaviour.
In order to ensure upgrade path and ability to switch back to HA queues
we change vhost names with removing leading `/`, as enabling quorum
requires to remove exchange which is tricky thing to do with running
services.
Change-Id: I9b9de6cdfac8ba3a89b874cd920df8d5b01e81f2
c15dc767fd