We need to handle the string returned by 'default' in the same way we handle
the string returned by 'status' since the resulting flags are compared later.
* Use the newly added 'default' argument to know if the default flags are set
or not.
* Handle that 'status' may either return flags or YES/NO.
* Centralize flag handling logic.
* Set action variable after check if we need to keep going.
Big thanks to @ajacoutot for implementing the rcctl 'default' argument.
* 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.
