Add initial base class for configuring pacemaker.

All other classes we add to use pacemaker to manage various services will go in
this module as well.
Merge pull request #131 from jguiditta/pacemaker_common

Add initial base class for configuring pacemaker.
Merge pull request #122 from gildub/neutron+fix-upstream-bridge-on-compute-nodes

Disable br-ex (or equivalent) to be created on compute nodes
Separated  parameters, hostgroups values from code; RSPEC added
rebasing master