Added monitoring with nagios

This new version is using an external puppet nagios module.
Which makes more sense since this is not directly related with openstack anyway.
This has the advantage to reduce impact on quickstack as much as possible.

This add a 'Nagios hostgroup' and monitoring::server and monitoring::client to wrap calls to the external nagios module. 

This is impacting only non HA to start with (Neutron/Nova_network controllers/compute/networker) 

Tested with latest RHOS5/RHEL7 

This requires:
* BZ#1118537 - Nagios plugins (load and disk) to be added to RHOS repos
* https://github.com/redhat-openstack/openstack-puppet-modules/pull/83
I kind of think this should default to '', otherwise we are assuming the default deployments are using nagios, which means staypuft will need to override in all cases to start until they are ready to support a nagios server.  Also, the latest build of opm does not yet have the nagios module in it, so I am testing by pulling that module over from source (ick)