Pin nokogiri module to 1.6.0
Pin nokogiri module to 1.6.0

gem install nokogiri -v '1.7.0.1' fails due to:
2017-01-06 08:37:23.086346 | Gem::InstallError: nokogiri requires Ruby
version >= 2.1.0.

Let's pin nokogiri to the previous version.

Change-Id: Ia9dbf6d16602661b6ba69b8b2f5219bef0fa4903
Closes-Bug: #1654520

openstack/puppet-pacemaker,openstack/puppet-pacemaker,openstack/puppet-pacemaker,openstack/puppet-pacemaker