Unpin beaker-rspec

Unpin beaker-rspec

The latest version of beaker tries to manage sshd_config[1] in order to
pass through environment variables. JJB also tries to manage
sshd_config by adding Match blocks to securely allow root SSH[2]. When
beaker tries to append the PermitUserEnvironment line after the Match
blocks, SSH fails to open port 22 and beaker can't SSH in to the
node[3]. This patch unpins beaker-rspec and adds set_env: false to the
nodepool nodesets so that the set_env method is never called and does
not try to mess with the sshd_config.

[1] https://github.com/puppetlabs/beaker/blob/master/lib/beaker/host_prebuilt_steps.rb#L528
[2] http://git.openstack.org/cgit/openstack-infra/project-config/tree/jenkins/jobs/puppet-module-jobs.yaml#n42
[3] http://logs.openstack.org/61/185161/1/check/gate-puppet-nova-puppet-beaker-rspec-dsvm-centos7/cd81608/console.html.gz#_2015-05-22_22_05_46_933
[4] https://github.com/puppetlabs/beaker/blob/master/lib/beaker/host_prebuilt_steps.rb#L502

Change-Id: Ia96c315a44d7ae90511d515b03166cbe5a060f31