Bring Redhat support to acceptance tests
OpenStack Infra has jobs to run this on both Ubuntu Trusty and CentOS7.
* Add minitest to Gemfile (dependency to run beaker on centos - see
http://projects.theforeman.org/issues/2650 for details)
* separate nodepool files to have trusty & centos7 support in OS infra
* basic_keystone_spec: add case for repo configuration and support
RH systems.
* rabbitmq: install module from source and on RH, install erlang before rabbitmq-server.
Change-Id: Ie6c823c7906afb37dd9e49fa434fefc3e26b5569
Closes-bug: #
1444736