Spike using nagios templates

In order to simplify the configuration of monitored_cron and even
increase the flexibility, pass in only nagios service templates.

Only timing and naming related parameters are kept, since those differ
per service.

Even active_checks_enabled can be solved via template now, in case you
still want to keep active service checks for a normally passivly
monitored service. This is useful while migrating from NRPE active checks to NCSA
based passive checks without monitoring state interruptions.

To keep existing behavior provide a nagios template for passive
services template on your nagios server like this
```puppet
nagios_service { 'generic-passive-service':
	use => 'generic-service',
	active_checks_enabled => 0,
	max_check_attempts => 1,
	notification_interval => (24 * 60),
	check_command => "check_dummy!3!received no check results for a long time, please investigate",
	register => 0,
}
```
and use it as the default template like this:
```puppet
class { 'puppet-periodicnoise::params':
	nagios_template => 'generic-passive-service',
}
```

@Bonko Please take a look.