Fix perfdata format for OS load (value=current;warning;critical)

[cinek810]

This is old Nagios style to return current value with warning and critical. It should not be used for 1 minute, 5 minute and 15 minutes, since those are just different measures and should be returned separately.

[stanvit]

Hi @cinek810 , thanks for the change
I'm a bit worrying about those who could still use the old style of System Load performance data, do you think that maybe it would be more backwards compatible to keep both formats? Would this format work for your use case?

perfdata.append('load=%s;%s;%s load1=%s load5=%s load15=%s'%(avg01,avg05,avg15,avg01,avg05,avg15))

[cinek810]

I see it's not backward compatible for former users of the plugin. Maybe instead of having two we should add a switch to enable new behavior? I can work on that - what do you think?
I don't like having both since it will likely double number of stats in the backend databases.

[stanvit]

I see it's not backward compatible for former users of the plugin. Maybe instead of having two we should add a switch to enable new behavior? I can work on that - what do you think? I don't like having both since it will likely double number of stats in the backend databases.

Yeah, having an option would be the best, I would appreciate if you added it.

Perhaps we should leave --load as it is and add a new parameter, something like --separate-la:

...
p.add_option("-L","--load", dest="process_la", action="store_true", default=False, help="Display load average performance data"
p.add_option("--separate-la", dest="separate_la", action="store_true", default=False, help="Display LA1, LA5 and LA15 values separately in performance data"
...
        if opts.process_la:
            process_system_load(service, opts.separate_la)
...
def process_system_load(service, separate_la=False):
    prefix = find_existing_prefix(service, ["system/load", "load"])
    ...
    if separate_la:
        perfdata.append('load1=%s load5=%s load15=%s'%(avg01,avg05,avg15))
    else:    
        perfdata.append('load=%s;%s;%s'%(avg01,avg05,avg15))