Install rabbitmq 3.3.5 for the beaker tests

The puppetlabs/rabbitmq (v 3.4.0 puppet module is incompatible with
rabbitmq 4.1. There is a PR open to make the puppetlabs module support
the latest version of rabbitmq:
https://github.com/puppetlabs/puppetlabs-rabbitmq/pull/250
Until a new puppetlabs/rabbitmq release comes out, we should install
rabbitmq 3.3.5 when we run the beaker tests.