add $::osfamily == 'RedHat' support
add param $enable_monit to class smartd

Used to enable/disable automatic declaration of a monit::monitor resource.  Default is false.
add param $devicescan_options to class smartd

used to pass arguments to the DEVICESCAN directive in smartd configuration file
rename class smartd param $schedule -> $warning_schedule to silence warning

Warning: schedule is a metaparam; this value will inherit to all contained resources in the smartd definition
rename class smartd param $scan -> $devicescan

it's slightly better 'self documenting' if the class params match the configuration file directives