Add ability to specify not to manage NRPE

[m-shaffer]

This would be a fairly big change, but it would be nice to be able to specify a manage_nrpe (default to true), and wrap all the nrpe and plugin installs in an if block. Also allowing the /etc/nagios/facter path to be overridden.

Doing this would allow this module to be compatible with windows if manage_nrpe is set to false.