* Make the module support enable/disable of special services like pf via rcctl.
Idea and method from @jarmani.
* Make the module handle when the user supplied 'arguments' variable does not
match the current flags in rc.conf.local.
* Update description now that the code tries to use rcctl for everything if it
is available.
Based on input from @jarmani:
* A return value of 2 now means a service does not exist. Instead of
trying to handle the different meanings of rc after running "status",
just look at stderr to know if something failed.
* Skip looking at stdout to make the code cleaner. Any errors should
turn up on stderr.
