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
* apt: pin the module
* heat encryption key parameter: use a valid length for the key
Change-Id: If9820a65f1310fe85ff43b32468b746268c04ea0
Closes-bug: #1444736