Add a pcmk_common file with some helper routines
Add a pcmk_common file with some helper routines

In this change we add a common lib/puppet/provider/pcmk_common.rb
file that will contain any function or routine that can be reused
across the different providers.

With this initial commit we add two routines that we will later make
use of:
- backup_cib() which takes a snapshot of the current live cluster CIB
  and stores it in a temporary file under /var/lib/pacemaker/cib/ and
  also makes a copy of it right away
- push_cib() takes a CIB file and pushes the CIB. If the pcs version
  supports it, it will use the "diff-against" syntax, which means that
  only the diff between the CIB file and the copy of the file made via
  backup_cib() will be sent to the cluster for processing.
  If the cib file and its original copy counterpart have no differences
  push_cib() is a noop

Change-Id: Icac6aac458031f5c0a08aac5f134976cf737e696

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