Add monit as an option for compute nodes

* Add use_monit (Default false) for site.pp
  If enabled, will install and configure monit watchdogs for
  specified services and roles (compute & cinder).
* Changes to cluster_ha.pp/cluster_simple.pp:
  - Add monit watchdogs for nova-compute/network/api for compute
    nodes by mathcing the python processes.
  - Add monit watchdogs for cinder-volume for cinder nodes
    by mathcing the python processes
  - Add monit watchdog for ovs service by its pid for computes.

DocImpact
Related blueprint pacemaker-improvements

Change-Id: Ia622d3200db1b78a0cf4e6b1da1ceff0604e8a16
Signed-off-by: Bogdan Dobrelya <bdobrelia@mirantis.com>
Merge "Add monit as an option for compute nodes"