Batteries check (megacli), perfdata, longoutput, and --noraidok option

Some improvements:
 - Batteries check for megacli plugin (based on @gbjtv's patch: glensc/nagios-plugin-check_raid#33),
 - Support of performance data and long text output,
 - New options -O / --noraidok to return OK instead of UNKNOWN if not RAID controller is found (based on @gbjtv's patch: glensc/nagios-plugin-check_raid#33).